2019年托福写作：TPO42综合写作阅读题目

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TPO-42 阅读文本和对应题目文本第3篇

Callisto and GanymedeFrom 1996 to 1999, the Galileo spacecraft passed through the Jovian system, providing much information about Jupiter's satellites. Callisto, the outermost of Jupiter's four largest satellites, orbits the planet in seventeen days at a distance from Jupiter of two million kilometers. Like our own Moon. Callisto rotates in the same period as it revolves, so it always keeps the same face toward Jupiter. Its noontime surface temperature is only about -140°C, so water ice is stable on its surface year-round. Callisto has a diameter of 4.820 kilometers, almost the same as that of Mercury. Its mass is only one-third as great, which means its density must be only one-third as great as well. This tells us that Callisto has far less of the rocky metallic materials found in the inner planets and must instead be an icy body through much of its interior.Callisto has not fully differentiated, meaning separated into layers of different density materials. Astronomers can tell that it lacks a dense core from the details of its gravitational pull on the Galileo spacecraft during several very close flybys. This fact surprised scientists, who expected that all the big icy moons would be differentiated. It is much easier for an icy body to differentiate than for a rocky one, since the melting temperature of ice is so low. Only a little heating will soften the ice and get the process started, allowing the rock and metal to sink to the center and the slushy ice to float to the surface. Y et Callisto seems to have frozen solid before the process of differentiation was complete.Like our Moon's highlands, the surface of Callisto is covered with impact craters. The survival of these craters tells us that an icy object can form and retain impact craters m its surface. In thinking of ice so far from the Sun, it is important not to judge its behavior from that of the much warmer ice we know on Earth; at the temperatures of the outer solar system, ice on the surface is nearly as hard as rock, and behaves similarly. Ice on Callisto does not deform or flow like ice in glaciers on Earth. Callisto is unique among the planet-sized objects of the solar system in its absence of interior forces to drive geological evolution. The satellite was born dead and has remained geologically dead for more than four billion years.Ganymede, another of Jupiter's satellites and the largest in our solar system, is also cratered, but less so than Callisto. About one-quarter of its surface seems to be as old and heavily cratered; the rest formed more recently, as we can tell by the sparse covering of impact craters as well as the relative freshness of the craters. Ganymede is a differentiated world, like the terrestrial planets. Measurements of its gravity field tell us that the rock and metal sank to form a core about the size of our Moon, with a mantle and crust of ice floating above it. In addition, the Galileo spacecraft discovered that Ganymede has a magnetic field, the signature of a partially molten interior. Ganymede is not a dead world, but rather a place of continuing geological activity powered by an internal heat source. Much of its surface may be as young as half a billion years.The younger terrain is the result of tectonic and volcanic forces Some features formed when the crust cracked, flooding many of the craters with water from the interior. Extensive mountain ranges were formed from compression of the crust, forming long ridges with parallel valleys spaced one to two kilometers apart. In some places older impact craters were split and pulled apart. There are even indications of large-scale crustal movements that are similar to the plate tectonics of Earth.Why is Ganymede different from Callisto? Possibly the small difference in size and internal heating between the two led to this divergence in their evolution. But more likely the gravity of Jupiter is to blame for Ganymede's continuing geological activity. Ganymede is close enough to Jupiter that tidal forces from the giant planet may have episodically heated its interior and triggered major convulsions on its crust.paragraph 1From 1996 to 1999, the Galileo spacecraft passed through the Jovian system, providing much information about Jupiter's satellites. Callisto, the outermost of Jupiter's four largest satellites, orbits the planet in seventeen days at a distance from Jupiter of two million kilometers. Like our own Moon. Callisto rotates in the same period as it revolves, so it always keeps the same face toward Jupiter. Its noontime surface temperature is only about -140°C, so water ice is stable on its surface year-round. Callisto has a diameter of 4.820 kilometers, almost the same as that of Mercury. Its mass is only one-third as great, which means its density must be only one-third as great as well. This tells us that Callisto has far less of the rocky metallic materials found in the inner planets and must instead be an icy body through much of its interior.1.According to paragraph 1, which of the following statements about Callisto is true?A.It is the satellite closest to Jupiter's surfaceB.Its surface temperature is constant at all times of the day.C. It has the same mass and diameter as the planet MercuryD. It completes one rotation every seventeen days.2. According to paragraph 1, how do scientists know that Callisto is made up largely of ice?A. A sample of its interior was taken by the Galileo spacecraft in the late 1990sB. It has too low a density to contain much rocky metallic materialC. With a noontime surface temperature of only about .140° C. the ice on it never meltsD. All of the bodies in the Jovian system are icy, because they are so far from the Sun.paragraph 2Callisto has not fully differentiated, meaning separated into layers of different density materials. Astronomers can tell that it lacks a dense core from the details of its gravitational pull on the Galileo spacecraft during several very close flybys. This fact surprised scientists, who expected that all the big icy moons would be differentiated. It is much easier for an icy body to differentiate than for a rocky one, since the melting temperature of ice is so low. Only a little heating will soften the ice and get the process started, allowing the rock and metal to sink to the center and the slushy ice to float to the surface. Y et Callisto seems to have frozen solid before the process of differentiation was complete.3.Why does the author provide the information that “It is much easier for an icy body to differentiate than for a rocky one”?A. To support the claim that all of the big icy moons are differentiatedB. To suggest that Callisto may be a rocky body rather than an icy oneC. To explain why scientists expected Callisto to be differentiatedD. To refute the claim that Callisto could not differentiate because it was frozen solid4.All of the following questions are answered in paragraph 2 EXCEPT:A.Why was Callisto frozen solid before differentiation was complete?B.What allows the process of differentiation to get started?C. Why is it easier for an icy body to differentiate than a rocky one?D. How do astronomers know that Callisto lacks a dense core?paragraph 3Like our Moon's highlands, the surface of Callisto is covered with impact craters. The survival of these craters tells us that an icy object can form and retain impact craters m its surface. In thinking of ice so far from the Sun, it is important not to judge its behavior from that of the much warmer ice we know on Earth; at the temperatures of the outer solar system, ice on the surface is nearly as hard as rock, and behaves similarly. Ice on Callisto does not deform or flow like ice in glaciers on Earth. Callisto is unique among the planet-sized objects of the solar system in its absence of interior forces to drive geological evolution. The satellite was born dead and has remained geologically dead for more than four billion years.5. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.A. It should not be assumed that surface ice has the same characteristics wherever it is foundB. Surface ice and rock are much more similar in temperature in the outer solar system than they are on Earth.C. The further away surface ice is from the Sun, the more its temperature differs from that of the warmer ice on EarthD. In the cold of the outer solar system, surface ice is so hard it behaves more like rock than like the warmer ice on Earth6.According to paragraph 3, how is Callisto different from all other planet-sized objects in the solar system?A. It can form and retain impact craters on its icy surfaceB. It has ice glaciers that do not flow or deform.C. It has never had the interior forces required for geological evolution.D. It is more than four billion years old.paragraph 4Ganymede, another of Jupiter's satellites and the largest in our solar system, is also cratered, but less so thanCallisto. About one-quarter of its surface seems to be as old and heavily cratered; the rest formed more recently, as we can tell by the sparse covering of impact craters as well as the relative freshness of the craters. Ganymede is a differentiated world, like the terrestrial planets. Measurements of its gravity field tell us that the rock and metal sank to form a core about the size of our Moon, with a mantle and crust of ice floating above it. In addition, the Galileo spacecraft discovered that Ganymede has a magnetic field, the signature of a partially molten interior. Ganymede is not a dead world, but rather a place of continuing geological activity powered by an internal heat source. Much of its surface may be as young as half a billion years.7.The word “signature” in the passage is closest in meaning toA.primary causeB.end resultC.identifying markD.by-product8. According to paragraph 4, each of the following provides evidence about Ganymede's interior EXCEPTA. Ganymede's large sizeB. measurements of Ganymede's gravity fieldC. the fact that Ganymede has a magnetic fieldD. the fact that Ganymede continues to be geologically activeparagraph 5The younger terrain is the result of tectonic and volcanic forces Some features formed when the crust cracked, flooding many of the craters with water from the interior. Extensive mountain ranges were formed from compression of the crust, forming long ridges with parallel valleys spaced one to two kilometers apart. In some places older impact craters were split and pulled apart. There are even indications of large-scale crustal movements that are similar to the plate tectonics of Earth.9.The word “Extensive” in the passage is closet in meaning toA.UnusualrgeC.NewD.Steep10. Paragraph 5 supports each of the following statements about Ganymede EXCEPT:A. All water on it has always been frozen solid.B. There is evidence that part of its crust once broke openC. Its crust has been subject to forces that have created mountains and valleys.D. Some of its older craters have been split apart by more recent geological activityparagraph 6Why is Ganymede different from Callisto? Possibly the small difference in size and internal heating between the two led to this divergence in their evolution. But more likely the gravity of Jupiter is to blame for Ganymede's continuing geological activity. Ganymede is close enough to Jupiter that tidal forces from the giant planet may have episodically heated its interior and triggered major convulsions on its crust.11. According to paragraph 6, the differences in how Callisto and Ganymede evoked are most probably due to differences in theirA. size and internal heatingB. distance from JupiterC. chemical and physical compositionD. age12.Look at the four squares [■] that indicate where the following sentence could be added to the passage.The difference between Ganymede and Callisto, however, extend much further below the surface of the satellites.Where would the sentence best fit? Click on square [■] to add the sentence to the passageGanymede, another of Jupiter's satellites and the largest in our solar system, is also cratered, but less so than Callisto. [■] About one-quarter of its surface seems to be as old and heavily cratered; the rest formed more recently, as we can tell by the sparse covering of impact craters as well as the relative freshness of the craters. [■] Ganymede is a differentiated world, like the terrestrial planets. [■] Measurements of its gravity field tell us that the rock and metal sank to form a core about the size of our Moon, with a mantle and crust of ice floating above it. [■] In addition, the Galileo spacecraft discovered that Ganymede has a magnetic field, the signature of a partially molten interior. Ganymede is not a dead world, but rather a place of continuing geological activity powered by an internal heat source. Much of its surface may be as young as half a billion years.13. Directions:An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selected THREE answer choices that express the most important ideas in the passage.Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage.This question is worth 2 points.Drag your choices to the spaces where they belong. To review the passage, click on View TextBetween 600 B.C. and 450 B.C., Athens changed the distribution of political power betweenthe aristocracy and ordinary citizens.CallistoGanymede阅读三Answer ChoicesA. It has a core that consists mainly of rock and metal.B. It may have formed as recently as half a billion years agoC. Its interior is not fully solidD. Its evolution has probably been strongly influenced by Jupiter's gravityE. It always keeps the same face toward Jupiter as it orbits the planetF. Its crust is covered by slow-moving glaciersG. Its entire surface is heavily cratered。

TPO 42 托福独立写作

When it comes to the question that whether a worker like to have different types of tasks a day or to do some similar task for the whole day, there is always some heat debates among the public. Some people may claim that doing different types of works is more attractive because they are less likely to get tired off if they could switch their focus for one task to another. However, as for me, I would like to only focus on similar tasks for the all day. My reasons are listed below.First of all, focusing on similar tasks could help me to do some work repeatedly and spare your time and effort on (一些特定的技巧)（要把原因讲一下）sharpen some particular professional skill and thus be more specialized in some field. Under such circumstances, I could significantly enhance my working efficiency. Take myself as an example. 用艺术/科技方面来举例（例子要将原因）Under such circumstances, I gradually become the expert in this particular field and quickly get promoted as the director specialized in Bank Account in the company. Therefore, it is of great importance to focus on a particular task, which helps you to get improved effectively.（影响，你可能在这个专业就很厉害）（概述要论点的原因和影响都要写，例子也是。

托福写作TPO42独立题目+综合写作文本

在托福写作练习过程中，相信TPO材料中的作文题目都会是大家的首选练习材料。

所以小编给考生们带来了托福写作TPO42，希望可以帮助广大托福考生轻松备考托福。

托福TPO42综合写作TASK 1 Integrated WritingGlass is a favored building material for modern architecture, yet it isalso very dangerous for wild birds. Because they often cannot distinguishbetween glass and open air, millions of birds are harmed every year when theytry to fly through glass windows. There are, however, several solutions thatresponsible businesses can use to prevent injuries to birds.One-Way GlassOne solution is to replace the regular, clear glass with one-way glass thatis transparent in only one direction. The occupants of the building can see out,but birds and others cannot see in. If birds cannot see through a window, theywill understand that the glass forms a solid barrier and will not try to flythrough it.Colorful DesignsA second solution is to paint colorful lines or other designs on regularwindow glass. For example, a window could have a design of thin stripes paintedover the glass. People would still be able to see through the openings in thedesign where there is no paint, while birds would see the stripes and thus avoidtrying to fly through the glass. Architects can be encouraged to includecolorful painted patterns on glass as part of the general design ofbuildings.Magnetic FieldThe third solution is to create an artificial magnetic field to guide birds away from buildings. Humans use an instrument called a magnetic compass to determine directions—either north, south, east, or west. Bird research has shown that birds have a natural ability to sense Earth’s magnetic fields; this ability works just like a compass, and it helps birds navigate in the right direction when they fly. A building in a bird flight path can be equipped with powerful electromagnets that emit magnetic signals that steer birds in a direction away from the building.DirectionsYou have 20 minutes to plan and write your response. Your response will be judged on the basis of the quality of your writing and on how well your response presents the points in the lecture and their relationship to the reading passage. Typically, an effective response will be 150 to 225 words.Essay TopicSummarize the points made in the lecture, being sure to explain how theycast doubt on the specific solutions proposed in the reading passage.You must finish your answer in 20 minutes托福TPO42独立写作TASK 2 Independent WritingDirectionsRead the question below. You have 30 minutes to plan, write, and reviseyour essay. Typically, an effective response will contain a minimum of 300 words.Question:。

托福TPO42阅读Passage2原文文本+题目+答案解析

为了帮助大家高效备考托福，为大家带来托福TPO42阅读Passage2原文文本+题目+答案解析，希望对大家备考有所帮助。

2019年10月12日托福写作考试真题及答案

2019年10月12日托福写作考试真题及答案刚过去的托福考试相信大家都很感兴趣，题目有多难？答案是怎样的？就跟着店铺来一起看一看2019年10月12日托福写作考试真题及答案。

上午场：Integrated WritingReading觉得Guillemots 的几个特点一点都不独特，但是听力说这几个特点还是很独特的。

1.阅读认为special colors and patterns；但是听力说guillemots和其他的鸟类住在一起，这个颜色和图案会帮助它们识别自己的蛋；2.阅读觉得蛋的表面很rough；但是听力认为这个鸟的蛋表面是脏，雨水会把他冲刷干净；3.阅读认为蛋的形状不能阻止guillemot的蛋掉下石头；但是听力说蛋的形状让雏鸟keep warm，可以躲避严寒天气；Independent WritingThere are many news stories about current event that helps people take a break from reading or listening to the news for a few days or weeks. Do you agree or disagree with the following statement， it is beneficial to stop reading and listening to the news for a few days or weeks. use details and examples to illustrate. DO NOT USE memoried examples.题目长的千万要注意，他是有特定背景的，这样具体的场景更加考验考生的理解能力和思维表达能力，所以写作固然是没有修改样式和考试方式，但是写作的题目难度是提高了不少；立场：在关于一些让人休闲和娱乐的时事新闻和故事如此多的时候，几天和几周停止看这些新闻是好的；知识/思维：一直看类似的新闻，会让自己的思维方式固定，不能灵活多变接受新的变化，所以停下来不看这些新闻一小段时间，让人们的脑子放空这样可以多方位思考；效率：停下来不看这些新闻一小段时间，会把时间省下来专注到自己的生活和工作，才能不分心，这样加快效率；个性：一直贪图新鲜和轻松看时事新闻，会让人称沉浸在放松的状态下，这样在后面的工作学习中会养成不良好的习惯，但是停下来会意识到自己的问题，去培养良好习惯；下午场：Integrated Writing关于应不应该被保护Prairie dogs；Independent Writing选一个活动对14-18岁的年轻人最有益gaining working experience/play sports/play music instrument。

TPO42综合写作听力原文：

托福TPO42综合写作听力原文文本：Professor: None of the solutions you've read about will effectively stop birds from getting injured.First, replacing regular glass with one-way glass. Well, the problem with one-way glass is that to the bird on the outside, a one-way glass surface reflects just like a mirror, and a surface that reflects like a mirror is just as bad as regular glass for birds because birds don't understand the mirrors. If they see a reflection of the sky in a mirror or of a tree in a mirror, they'd think the reflection is the sky or is the tree. And they'll fly right into them.The second solution, painting colorful patterns like stripes on regular glass, also has problems. As the reading said, these designs include openings so people inside the buildings can see out, but birds will perceive these unpainted openings as open holes. And if birds think that they are seeing holes, they'll try to fly right through them. To prevent birds from doing this, the unpainted spaces in a window would have to be extremely small, but that would then make the rooms of the buildings too dark for the people inside them.The third solution, creating an artificial magnetic field, won't work very well either. While it's true that birds use Earth's magnetic field to help them navigate, they use this only when they are travelling very long distances. For example, if a bird is migrating from a cold country to a warm one before winter, it will use its magnetic sense to figure out which way it should fly. But this ability isn't used to go over short distances, such as going from one side of the city to another. For short trips, birds use their eyes and the brightness of light to determine where to go. So magnetic signals from buildings won't have much effect.。

2019年托福写作：TPO42综合写作阅读题目.doc

2019 年托福写作： TPO42 综合写作阅读题目TPO42综合写作题目文本Integrated WritingGlass is a favored building material for modern architecture, yet it is also very dangerous for wild birds. Because they often cannot distinguish between glass andopen air, millions of birds are harmed every year when they tryto fly through glass windows. There are, however, several solutions that responsible businesses can use to preventinjuries to birds.One-Way GlassOne solution is to replace the regular, clear glass withone-way glass that is transparent in only one direction. The occupants of the building can see out, but birds and others cannot see in. If birds cannot see through a window, theywill understand that the glass forms a solid barrier and willnot try to fly through it.Colorful DesignsA second solution is to paint colorful lines or other designs on regular window glass. For example, a window could have a design of thin stripes painted over the glass. People would stillbe able to see through the openings in the design where thereis no paint, while birds would see the stripesand thus avoid trying to fly through the glass. Architectscan be encouraged to include colorful painted patterns onglass as part of the general design of buildings.Magnetic FieldThe third solution is to create an artificial magneticfield to guide birds away from buildings. Humans use aninstrument called a magnetic compass to determinedirections —either north, south, east, or west. Bird researchhas shown that birds have a natural ability to sense Earth’s magnetic fields; this ability works just like a compass, andit helps birds navigate in the right direction when they fly.A building in a bird flight path can be equipped withpowerful electromagnets that emit magnetic signals that steerbirds in a direction away from the building.DirectionsTPO42综合写作You have 20 minutes to plan and write your response.Your response will be judged on the basis of the quality of yourwriting and on how well your response presents the points in thelecture and their relationship to the reading passage. Typically,an effective response will be 150 to 225 words.Essay TopicTPO42综合写作Summarize the points made in the lecture, being sure toexplain how they cast doubt on the specific solutionsproposed in the reading passage.You must finish your answer in 20 minutes。

TPO阅读42文本答案翻译

TPO-42Geographic Isolation of SpeciesBiologist Ernst Mayr defined a species as “an actually or potentially interbreeding population that does notthe separation of a population with its gene pool (all of the genes in a population at any one time) from other populations of the same species, thereby preventing population interbreeding. With its gene pool isolated, a separate population canbeen a geographic barrier. This mode of evolving new species is called allopatric speciation.Many factors can isolate a population geographically. A mountain range may emerge and gradually split a population of organisms that can inhabit only lowland lakes, certain fish populations might become isolated in this way. Similarly, a creeping glacier may gradually divide a population, or a land bridge such as the Isthmus of Panama may form and separate the marine life in the ocean waters on either side.Too many words you don’t know? Look them up in《新托福TPO阅读词汇速查速记》!Wechat: geeqi0805How formidable must a geographic barrier be to keep populations apart? It depends on the ability of the organisms to move across barriers. Birds and coyotes can easily cross mountains and rivers. The passage of wind-blown tree pollen is also not hindered by such barriers, and the seeds of many plants may be carried back and forth on animals In contrast, small rodents may find a deep canyon or a wide river an effective barrier. For example, the Grand Canyon, in the southwestern United States, separate the range of the while-tailed antelop e squirrel from that of the closely related Harris’ antelope squirrel. Smaller, with a shorter tail that is white underneath, the white-tailed antelope squirrel inhabits deserts north of the canyon and west of the Colorado River in southern California Hams' antelope squirrel has a more limited range in deserts south of the Grand Canyon.Geographic isolation creates opportunities for new species to develop, but it does not necessarily lead to newbetween the isolated population and its parent population. The likelihood of allopatric speciation increases when a population is small as well as isolated, making it more likely than a large population to have its gene pool changed substantially. For example, in less than two million years, small populations of stray animals and plants from the SouthAmerican mainland to colonize the Galapagos Islands gave rise to all the species that now inhabit the islands.When oceanic islands are far enough apart to permit populations to evolve in isolation, but close enough to allow occasional dispersions to occur, they are effectively outdoor laboratories of evolution. The Galapagos island chain is one of the world’s greatest showcases of evolution. Each island was born from underwater volcanoes and was gradually covered by organisms derived from strays that rode the ocean currents and winds from other islands and continents. Organisms can also be carried to islands by other organisms, such as sea birds that travel long distances with seeds clinging to their feathers.The species on the Galapagos Islands today, most of which occur nowhere else, descended from organisms that floated, flew, or were blown over the sea from the South American mainland. For instance, the Galapagos island chainhas a total of thirteen species of closely related birds called Galapagos finches. These birds have many similarities but differ in their feeding habits and their beak type, which is correlated with what they eat. Accumulated evidence indicates that all thirteen finch species evolved from a single small population of ancestral birds that colonized one of the islands. Completely isolated on the island after migrating from the mainland, the founder population may have undergone significant changes in its gene pool and become a new species. ■Later, a few individuals of this new species may have been blown by storms to a neighboring island. ■Isolated on this second island, t he second founder population could have evolved into a second new species, which could later recolonize the island from which its founding population emigrated. ■Today each Galapagos island has multiple species of finches, with as many as ten on some islands. ■A. earlyB. crucialC. noticeableD. frequentA. bestB. usualC. firstD. actualYou enjoy the convenience of having all vocabulary questions listed as a separate part in《新托福TPO阅读词汇速查速记》.3. According to paragraph 1, allopatric speciation is possible whenA. a population contains all the different genes present in a species at a particular timeB. a population becomes isolated due to the presence of a geographic barrierC. genetic mixing begins to occur in previously separate populations of a speciesD. a species is successful in crossing a geographic barrier4. How is paragraph 2 related to paragraph 1?A. Paragraph 2 points out a number of ways in which the phenomenon of geographic isolation mentioned in paragraph 1 can occurB. Paragraph 2 identifies discoveries that led to the conclusion presented in paragraph 1 that geographic isolation has played a role in the origin of many speciesC. Paragraph 2 provides evidence supporting the statement in paragraph 1 that a population can follow its own evolutionary course once its gene pool becomes isolatedD. Paragraph 2 explains why the term “allopatric” was adopted to describe the method of speciation described in paragraph 15. In paragraph 3, the author contrasts a variety of organisms to illustrate which of the following points?A. Geographic barriers are less likely to keep apart populations of plants than populations of animalsB. Geographic barriers are more likely to keep apart populations of large organisms than populations of small organismsC. Some members of a species are able to cross geographic barriers, while other members of the same species are notD. The effectiveness of geographic barriers in keeping organisms apart depends on an organism’s ability to move across barriers6. Paragraph 3 supports the idea that white-tailed antelope squirrels and Hams' antelope squirrels have which of the following in common?A. They are the two smallest rodents now found in the southwestern United States.B. They have white coloring underneath their tailsC. They cannot cross the Grand CanyonD. They cannot survive in desert conditionsA. experiencesB. allowsC. preventsD. causes8. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential informationA. Geographic isolation is sometimes but not always the reason for the creation of reproductive barriers between a parent population and the populations descended from itB. Genetic changes in a geographical isolated population do not necessarily make the population look different enough from its parent population to be considered a new speciesC. Geographical isolation allows the separated populations to evolve independently of each other and so can lead to the formation of new speciesD. Geographic isolation can lead to new species only if the gene pool of the isolated population changes enough to prevent it from reproducing with the parent population9. According to paragraph 4, why does the size of a population affect the likelihood of allopatric speciation?A. Because smaller populations are more likely than larger ones to become geographically isolatedB. Because the gene pool of a small isolated population is more likely to undergo substantial change than is the gene pool of a larger populationC. Because an isolated population can become a new species with substantially less change to its gene pool than would be required by a larger populationD. Because smaller populations are more likely to be made up of stray animals or plants than larger populations areA. were ableB. were forcedC. arrivedD. expanded11. Paragraph 5 supports the idea that the Galapagos island chain was able to become “one of the world's greatest showcases of evolution” primarily because ofA. the richness of the volcanic soil of each of the islands in the chainB. the distance of the individual islands from each other and from the mainlandC. the relativity long time it took for the islands to become covered by organismsD. the outdoor laboratories that scientists have built on the islands to study evolution12. According to paragraph 6, what is true about the thirteen species of Galapagos finches?A. All thirteen species are now found on most of the Galapagos IslandsB. All thirteen species are descended from the same population of ancestral birdsC. All thirteen species evolved on the island that was originally colonized by finches from the mainland.D. All thirteen species occur only in small, completely isolated populations.13. Look at the four squares [█] that indicate where the following sentence could be added to the passageThis process of speciation and colonization could have been repeated over and over again, gradually involving all the islands in the chain.Where would the sentence best fit? Click on a square to add the sentence to the passage.14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. The question is worth 2 points.The geographic isolation of a population can result in the rise of a new species.●●●Answer Choices○ Isolation can result when a geographic barrier forms and splits a population or when a few organisms somehow get carried across an existing geographic barrier and form a new population○ Speciation is more likely when an isolated population is small because significant genetic changes are more likely to occur in a small population than in a large one○ Because of the geographic isolation of the Galapagos Islands, the species that now inhabit them have gene pools that have not changed very much since the islands were first populated.○ Fish populations are more easily isolated by geographic barriers than are populations of most other organisms because fish cannot move across areas where there is no water.○ The Galapagos Islands are well situated for speciation because they provide opportunities for population isolation while also making occasional dispersions between islands possible.○ Evidence indicates t hat the first organisms to reach the Galapagos Islands were probably a small population of finches that, in less than two million years of isolation, evolved into thirteen species.答案：1-5: B C B A D 6-10:C A D B A 11-14: B B C A B EIf you have any questions concerning the texts or answers, feel free to contact Wechat: geeqi0805.If you are tired of looking up TPO words in a dictionary, try《新托福TPO阅读词汇速查速记》!参考译文：物种的地理隔离生物学家厄恩斯特·迈尔将物种定义为“一个可以互相交配或可能互相交配的群体，但这个群体不能与其它生物交配，即便有交配的机会”。

托福TPO42口语Task3阅读文本+听力文本+题目+满分范文

为了帮助大家高效备考托福，为大家带来托福TPO42口语Task3阅读文本+听力文本+题目+满分范文，希望对大家备考有所帮助。

托福TPO42口语Task3阅读文本： No More Evening Classes The administration has announced that starting next fall, the university will stop offering evening classes in many departments. According to a university administrator, the decision was prompted by a steady decline in enrollments in evening classes. "Evening classes are just too small," the administrator said. When asked to explain the decline in enrollments, the administrator pointed to the fact that most evening classes are taught by teaching assistants, who are usually graduate students. “Surveys show that students prefer to take classes taught by experienced faculty members,” the spokesperson said, "probably because they simply know more than graduate teaching assistants do." 托福TPO42口语Task3听力文本： Now listen to two students discussing the article. Man：I just don't know about this decision. Woman：It sort of makes sense to me. Man：Not to me. I don't understand their reasoning. I mean, what's wrong with small classes? I think that's what students actually prefer. And it's easy to see why. Woman：Yeah. You do get to participate more. Man：Definitely. You can be more actively involved, get more attention and support. It's just a better way to learn. Woman：Okay. But there is that survey. Man：I don't know what students they asked, but I know a lot of people who feel just the opposite. I mean, what does experience mean anyway? Sometimes it means you have been teaching the same subject for twenty years and you are probably tired of it by now and maybe not very enthusiastic. Woman：Yeah. That does happen. Man：Whereas if it's the first time or maybe second you are teaching a class,well, it's going to be more exciting to you. And you are going to communicate that excitement to the people you are teaching. At least that's how I see it. 托福TPO42口语Task3题目： The man disagrees with the decision announced in the student newspaper. Explain why the university made the decision and why the man disagrees with it. 托福TPO42口语Task3满分范文： The school has implemented a new policy that the university will stop offering evening classes in many departments starting next fall due to the small scale of them and the unexperienced teaching staff. And the man holds a negative view towards the announcement. The first reason he gives is that thanks to the small classes, students can participate more and be more actively involved, get more attention and learn more. And the second one is based on the fact that some experienced teachers are lack of enthusiasm because they may have been teaching the same subject for too long. In contrast, if this is their first or second time teaching a class, it’s going to be so exciting to them and they’ll definitely dedicate more. Therefore, he disagrees with that opinion. 以上是给大家整理的托福TPO42口语Task3阅读文本+听力文本+题目+满分范文，希望对你有所帮助!。

托福阅读真题第42篇TheEvolutionofPlantRoots

托福阅读真题第42篇TheEvolutionofPlantRoots托福阅读真题第42篇The Evolution of Plant RootsThe Evolution of Plant RootsRoots are essential to the development of large plants because they provide a means of anchoring and maintaining an upright position.Most land plants are literally rooted to the spot.Roots also play a key role in water and nutrient acquisition.More significantly still, roots have a tremendous impact on the environment. They can break up rock, bind loose particles together, and prov idea conduit for the movement of water and dissolved minerals,all of which are essential to the development of soils.In piecing together a fossil plant to form a conceptual whole, it is usually the rooting system that remains the final piece in the puzzle. It is often the case that roots are poorly studied or completely unknown.Although the fossil record of roots is therefore less complete than that of other plant organ systems, it is possible to discern some general trends.The earliest land plants, like modern mosses and liverworts,did not have well-developed root systems.These plants simply bore absorbing hairlike cells on stems and leaves that grew flat along the ground.From their fossils,some very early plants are known to have borne branches that appear to be specially modified for rooting. In other cases, roots were able to form from dormant buds on aerial stems.Fungi are also known to have played a key role in these early rooting systems, as they do in modern plants.Fungal symbionts—fungi that live in mutually beneficial relationships with another organism-have been recorded in the petrified plants of the 400million-year-old Rhynie Chert fossil sitein Scotland, demonstrating a link with mycorrhizal fungi that goes back to the dawn of the land flora.These tiny, shallow rooting systems were adequate for small plants (30-50 centimeters tall), but larger organisms required something more substantial.By the Late Devonian and Early Carboniferous eras (385 to 300 million years ago), an enormous variety of rooting structures had evolved.The evolution of large erect plants, and in particular trees,placed increasing demands upon the anchoring and supply functions of roots.These problems were solved mainly through the development of more extensive underground systems.The evolution of the cambium, the layer of living cells between wood and bark,enabled continuous perennial growth and long-term survival of roots in soils.One important consequence of all this was that there was a progressive and massive increase in root biomass during the Devonian, which had an enormous impact on the development of soils. Prior to the Devonian,soils, if developed at all, are thought to have been predominantly thin and of microbial origin. By the Middle Devonian,soil penetration depths of roots were still shallow(less than 20 centimeters), but this increased to 1 meter or more as forests spread.The diversity of soils also increased.This change was brought about by root-induced weathering and mixing. By the end of the Devonian, there was an increase in soil clay content,structure,and differentiation into distinct layers—a development that correlated with increases in depth of root penetration. Soils with modern profiles(series of layers) are recognizable at this time.The impact of roots on the environment extends beyond their immediate effects on the development of soils.The presenceof roots in soils increases the natural weathering of calcium and magnesium silicate minerals.This apparently mundane fact turns out to have extremely important consequences for climate and temperature globally. Under natural circumstances, calcium and magnesium silicates react chemically with a dissolved form of the gas carbon dioxide (a process referred to as weathering), which comes from the atmosphere.This produces calcium and magnesium carbonates,which are transferred through the groundwater system to rivers and ultimately to the oceans, where they accumulate in the form of limestone and dolomite rock.Across the surface of the Earth, these chemical reactions occur on a vast scale, removing carbon dioxide gas from the atmosphere and locking it up as carbonate in rock formations. This reduces the so-called greenhouse effect, which leads to lower global temperatures. In other words, the widespread development of roots in land plants affected the chemistry of the atmosphere and the oceans, which, summed over millions of years,added up to changes in climate on a global scale.1.Roots are essential to the development of large plants because they provide a means of anchoring and maintaining an upright position.Most land plants are literally rooted to the spot.Roots also play a key role in water and nutrient acquisition.More significantly still, roots have a tremendous impact on the environment. They can break up rock, bind loose particles together, and prov idea conduit for the movement of water and dissolved minerals,all of which are essential to the development of soils.2.In piecing together a fossil plant to form a conceptual whole, it is usually the rooting system that remains the final piecein the puzzle. It is often the case that roots are poorly studied or completely unknown.Although the fossil record of roots is therefore less complete than that of other plant organ systems, it is possible to discern some general trends.The earliest land plants, like modern mosses and liverworts,did not have well-developed root systems.These plants simply bore absorbing hairlike cells on stems and leaves that grew flat along the ground.From their fossils,some very early plants are known to have borne branches that appear to be specially modified for rooting. In other cases, roots were able to form from dormant buds on aerial stems.Fungi are also known to have played a key role in these early rooting systems, as they do in modern plants.Fungal symbionts—fungi that live in mutually beneficial relationships with another organism-have been recorded in the petrified plants of the 400million-year-old Rhynie Chert fossil site in Scotland, demonstrating a link with mycorrhizal fungi that goes back to the dawn of the land flora.These tiny, shallow rooting systems were adequate for small plants (30-50 centimeters tall), but larger organisms required something more substantial.3.In piecing together a fossil plant to form a conceptual whole, it is usually the rooting system that remains the final piece in the puzzle. It is often the case that roots are poorly studied or completely unknown.Although the fossil record of roots is therefore less complete than that of other plant organ systems, it is possible to discern some general trends.The earliest land plants, like modern mosses and liverworts,did not have well-developed root systems.These plants simply bore absorbing hairlike cells on stems and leaves that grew flat along theground.From their fossils,some very early plants are known to have borne branches that appear to be specially modified for rooting. In other cases, roots were able to form from dormant buds on aerial stems.Fungi are also known to have played a key role in these early rooting systems, as they do in modern plants.Fungal symbionts—fungi that live in mutually beneficial relationships with another organism-have been recorded in the petrified plants of the 400million-year-old Rhynie Chert fossil site in Scotland, demonstrating a link with mycorrhizal fungi that goes back to the dawn of the land flora.These tiny, shallow rooting systems were adequate for small plants (30-50 centimeters tall), but larger organisms required something more substantial.4.By the Late Devonian and Early Carboniferous eras (385 to 300 million years ago), an enormous variety of rooting structures had evolved.The evolution of large erect plants, and in particular trees,placed increasing demands upon the anchoring and supply functions of roots.These problems were solved mainly through the development of more extensive underground systems.The evolution of the cambium, the layer of living cells between wood and bark,enabled continuous perennial growth and long-term survival of roots in soils.5.One important consequence of all this was that there wasa progressive and massive increase in root biomass during the Devonian, which had an enormous impact on the development of soils. Prior to the Devonian,soils, if developed at all, are thought to have been predominantly thin and of microbial origin. By the Middle Devonian,soil penetration depths of roots were stillshallow(less than 20 centimeters), but this increased to 1 meter or more as forests spread.The diversity of soils also increased.This change was brought about by root-induced weathering and mixing. By the end of the Devonian, there was an increase in soil clay content,structure,and differentiation into distinct layers—a development that correlated with increases in depth of root penetration. Soils with modern profiles(series of layers) are recognizable at this time.6.One important consequence of all this was that there wasa progressive and massive increase in root biomass during the Devonian, which had an enormous impact on the development of soils. Prior to the Devonian,soils, if developed at all, are thought to have been predominantly thin and of microbial origin. By the Middle Devonian,soil penetration depths of roots were still shallow(less than 20 centimeters), but this increased to 1 meter or more as forests spread.The diversity of soils also increased.This change was brought about by root-induced weathering and mixing. By the end of the Devonian, there was an increase in soil clay content,structure,and differentiation into distinct layers—a development that correlated with increases in depth of root penetration. Soils with modern profiles(series of layers) are recognizable at this time.7.The impact of roots on the environment extends beyond their immediate effects on the development of soils.The presence of roots in soils increases the natural weathering of calcium and magnesium silicate minerals.This apparently mundane fact turns out to have extremely important consequences for climate and temperature globally. Under natural circumstances, calcium andmagnesium silicates react chemically with a dissolved form of the gas carbon dioxide (a process referred to as weathering), which comes from the atmosphere.This produces calcium and magnesium carbonates,which are transferred through the groundwater system to rivers and ultimately to the oceans, where they accumulate in the form of limestone and dolomite rock.Across the surface of the Earth, these chemical reactions occur on a vast scale, removing carbon dioxide gas from the atmosphere and locking it up as carbonate in rock formations. This reduces the so-called greenhouse effect, which leads to lower global temperatures. In other words, the widespread development of roots in land plants affected the chemistry of the atmosphere and the oceans, which, summed over millions of years,added up to changes in climate on a global scale.8.The impact of roots on the environment extends beyond their immediate effects on the development of soils.The presence of roots in soils increases the natural weathering of calcium and magnesium silicate minerals.This apparently mundane fact turns out to have extremely important consequences for climate and temperature globally. Under natural circumstances, calcium and magnesium silicates react chemically with a dissolved form of the gas carbon dioxide (a process referred to as weathering), which comes from the atmosphere.This produces calcium and magnesium carbonates,which are transferred through the groundwater system to rivers and ultimately to the oceans, where they accumulate in the form of limestone and dolomite rock.Across the surface of the Earth, these chemical reactions occur on a vast scale, removing carbon dioxide gas from the atmosphere and locking it up as carbonate in rock formations.This reduces the so-called greenhouse effect, which leads to lower global temperatures. In other words, the widespread development of roots in land plants affected the chemistry of the atmosphere and the oceans, which, summed over millions of years,added up to changes in climate on a global scale.9.Roots are essential to the development of large plants because they provide a means of anchoring and maintaining an upright position.⬛Most land plants are literally rooted to the spot.⬛Roots also play a key role in water and nutrient acquisition.⬛More significantly still, roots have a tremendous impact on the environment. ⬛They can break up rock, bind loose particles together, and prov idea conduit for the movement of water and dissolved minerals,all of which are essential to the development of soils.10.答案如下：.42篇The Evolution of Plant Roots。

tpo42综合写作

Three solutions are proposed in the reading passage to prevent injuries caused by glass used to birds in the buildings. However, the professor in the lecture contradicts all of them.First of all, the author argues that the regular, clear glass can be replaced byone-way glass, sothat the birds can not see through fromoutside andthus will notfly through the glass window. By contrast, the professor refutes this solution by claimingthat the one-way glass actually works as a mirror when seen fromoutside,whose impact will be as bad as the regular glass because birds do not understand the functions of mirror, on whose surface trees and the sky will be reflected, sobirds will think it is the same as the natural world.Second, the author states that architects can paint colorful lines and designson regular glass window, and when birds see the stripes from outside, they willavoid flying through the window. On the contrary, the professor maintains that even with colorful designs there will be unpainted openings on the window looking just like open holes, so birds may still fly through those holes. In order to prevent it fromhappening, the unpaintedspaces must be small enough. But in thiscase, the room will be too dark.Third, the reading proposes that humans can install artificial magnetic field on buildingtohelpbirds navigate away frombuildings. However, the professor insiststhat birds actually use magnetic signals to navigate only when they migrate a longway such as when they migrate fromcoldareas towarmareas duringspring. But ifthey are on a short trip, they wouldrely on their eyes to navigate. So the magneticdevice will not be effective, either.。

tpo42独立写作范文

tpo42独立写作范文There are different standpoints regarding the happiness from the work. Some argue that workers would gain more satisfaction from doing different types of tasks while others hold the opposite idea that to do the same task leads them to be happier. In fact, it is hard to judge and up to the context of the work.Obviously, the majority of people are reluctant to repeat their action mechanically, because they cannot endure the tediousness created by the same work. Trying to do different types of tasks is beneficial for them to keep the motivation of job and is easy to satisfy themselves with achieving success in varied domains. Meanwhile, however, other consequences as a result from dissimilar sorts of work are supposed to be taken into account as well.The different types of tasks would make it impossible for workers to be happy sometimes: they coerce these people to face new challenges and it costs more time to acquaint every kind of tasks which even would be changed definitely in the second day. Except few extremely bold people, a huge number of workers willfeel quite stressful when something is completely new for them. Further, the same type of task doesn’t mean the context of the job is the same. People are likely to suffer from varied kinds of in the daily work. An architect should do several different plans for one project. Even though they draw a window for one building’s , they have to establish dozens of models of windows to match the whole genre. Besides, if their work does not f ulfill their customers’ demands, the architects have no choice but to redraw the . This type of work on some stage can also be called working repeatedly, whereas the context is definitely different and filled with challenges. It affords the strong happiness when the clients acclaim the work at last. So, I believe that no one will affirm that being an architect is a boring position even though they only do design every day.Consequently, we have to clarify which reasons lead workers to be happy. How different the type of tasks is unlikely to simply determine how happy workers can be during their workday. If one type of task containing diverse challenges stimulates someone’s motivation, the people would attain likewise pleasure from the work.。

托福TPO42阅读文本

托福TPO42阅读文本+题目+答案下载Geographic Isolation of SpeciesBiologist Ernst Mayr defined a species as “an actually or potentially interbreeding population that does not interbreed with other such populations when there is opportunity to do so.”A key event in the o rigin of many species is the separation of a population with its gene pool (all of the genes in a population at any one time) from other populations of the same species, thereby preventing population interbreeding With its gene pool isolated, a separate population can follow its own evolutionary course. In the formation of many species, the initial isolation of a population seems to have been a geographic barrier This mode of evolving new species is called allopatric speciation.Many factors can isolate a population geographically.A mountain range may emerge and gradually split a population of organisms that can inhabit only lowland lakes, certain fish populations might become isolated in this way. Similarity, a creeping glacier may gradually divide a population, or a land bridge such as the Isthmus of Panama may form and separate the marine life in the ocean waters on either side. How formidable must a geographic barrier be to keep populations apart? It depends on the ability of the organisms to move across barriers.Birds and coyotes can easily cross mountains and rivers. The passage of wind-blown tree pollen is also not hindered by such barriers, and the seeds of many plants may be earned back and forth on animals In contrast, small rodents may find a deep canyon or a wide river an effective barrier. For example, the Grand Canyon, in the southwestern United Slates, separate the range of the while-tailed antelope squirrel from that of the closely related Harris’ antelope squirrel. Smaller, with a shorter tail that is white underneath, the white-tailed antelope squirrel inhabits deserts north of the canyon and west of the Colorado River in southern California Hams' antelope squirrel has a more limited range in deserts south of the Grand Canyon.Geographic isolation creates opportunities for new species to develop, but it does not necessarily lead to new species because speciation occurs only when the gene pool undergoes enough changes to establish reproductive barriers between the isolated population and its parent population.The likelihood of allopatricspeciation increases when a population is small as well as isolated, making it more likely than a large population to have its gene pool changed substantially. For example,in less than two million years, small populations of stray animals and plants from the South American mainland that managed to colonize the Galapagos Islands gave rise to all the species that now inhabit the islands.When oceanic islands are far enough apart to permit populations to evolve in isolation, but close enough to allow occasional dispersions to occur, they are effectively outdoor laboratories of evolution.The Galapagos island chain is one of the world s greatest showcases of evolution Each island was born from underwater volcanoes and was gradually covered by organisms derived from strays that rode the ocean currents and winds from other islands and continents. Organisms can also be carried to islands by other organisms, such as sea birds that travel long distances with seeds clinging to their feathers.The species on the Galapagos Islands today, most of which occur nowhere else, descended from organisms that floated, flew, or were blown over the sea from the South American mainland For instance, the Galapagos island chain has a total of thirteen species of closely related birds called Galapagos finches These birds have many similarities but differ in their feeding habits andtheir beak type, which is correlated with what they eat Accumulated evidence indicates that all thirteen finch species evolved from a single small population of ancestral birds that colonized one of the pletely isolated on the island after migrating from the mainland, the founder population may have undergone significant changes in its gene pool and become a new species. Later, a few individuals of this new species may have been blown by storms to a neighboring island. Isolated on this second island, the second founder population could have evolved into a second new species, which could later recolonize the island from which its founding population emigrated.Today each Galapagos island has multiple species of finches, with as many as ten on some islands.paragraph 1Biologist Ernst Mayr defined a species as “an actually or potentially interbreeding population that does not interbreed with other such populations when there isopportunity to do so.” A key event in the origin of many species is the separation of a population with its gene pool (all of the genes in a population at any one time) from other populations of the same species, thereby preventing population interbreeding With its gene pool isolated, a separate population can follow its own evolutionary course. In the formation of many species, the initial isolation of a population seems to have been a geographic barrier This mode of evolving new species is called allopatric speciation.1.The word “key” in the passage is closest in meaning toA.earlyB.crucialC.noticeableD.frequent2.The word “initial” in the passage is closest in meaning toA.bestualC.firstD.actual3.According to paragraph 1. allopatric speciation is possible whenA. a population contains all the different genes present in a species at a particular timeB. a population becomes isolated due to the presence of a geographic barrierC. genetic mixing begins to occur in previously separate populations of a speciesD. a species is successful in crossing a geographic barrierparagraph 1&2Biologist Ernst Mayr defined a species as “an actually or potentially interbreeding population that does not interbreed with other such populations when there is opportunity to do so.”A key event in the origin of many species is the separation of a population with its gene pool (all of the genes in a population at any one time) from other populations of the same species, thereby preventing population interbreeding With its gene pool isolated, a separate population can follow its own evolutionary course. In the formation of many species, the initial isolation of a population seems to have been a geographic barrier This mode of evolving new species is called allopatric speciation.Many factors can isolate a population geographically. A mountain range may emerge and gradually split a population of organisms that can inhabit only lowland lakes, certain fish populations might become isolated in this way. Similarity, a creeping glacier may gradually dividea population, or a land bridge such as the Isthmus of Panama may form and separate the marine life in the ocean waters on either side.4.How is paragraph 2 related to paragraph 1?A. Paragraph 2 points out a number of ways in which the phenomenon of geographic isolation mentioned in paragraph 1 can occurB. Paragraph 2 identifies discoveries that led to the conclusion presented in paragraph 1 that geographic isolation has played a rote in the origin of many speciesC. Paragraph 2 provides evidence supporting the statement in paragraph 1 that a population can follow its own evolutionary course once its gene pool becomes isolatedD. Paragraph 2 explains why the term “allopatric” was adopted to describe the method of speciation described in paragraph 1paragraph 3How formidable must a geographic barrier be to keep populations apart? It depends on the ability of the organisms to move across barriers. Birds and coyotes can easily cross mountains and rivers. The passage of wind-blown tree pollen is also not hindered by such barriers, and the seeds of many plants may be earned back and forth on animals In contrast, small rodents may find a deep canyon or a wide river an effective barrier. For example, the Grand Canyon, in the southwestern United Slates, separate the range of the while-tailed antelope squirrel from that of the closely related Harris’ antelope squirrel. Smaller, with a shorter tail that is white underneath, the white-tailed antelope squirrel inhabits deserts north of the canyon and west of the Colorado River in southern California Hams' antelope squirrel hasa more limited range in deserts south of the Grand Canyon.5.In paragraph 3, the author contrasts a variety of organisms to illustrate which of the following points?A. Geographic barriers are less likely to keep apart populations of plants than populations of animals.B. Geographic barriers are more likely to keep apart populations of large organisms than populations of small organismsC. Some members of a species are able to cross geographic barriers, while other members of the same species are not.D. The effectiveness of geographic barriers in keeping organisms apart depends on an organism’s ability to mov e across barriers.6.Paragraph 3 supports the idea that white-tailed antelope squirrels and Hams' antelope squirrels have which of the following in common?A. They are the two smallest rodents now found in the southwestern United States.B. They have white coloring underneath their tailsC. They cannot cross the Grand CanyonD. They cannot survive in desert conditionsparagraph 4Geographic isolation creates opportunities for new species to develop, but it does not necessarily lead to new species because speciation occurs only when the gene pool undergoes enough changes to establish reproductive barriers between the isolated population and its parent population. The likelihood of allopatric speciation increases when a population is small as well as isolated, making it more likely than a large population to have its gene pool changed substantially. For example, in less than two million years, small populations of stray animals and plants from the South American mainland that managed to colonize the Galapagos Islands gave rise to all the species that now inhabit the islands.7.The word “undergoes” in the passage is closest in meaning toA.experiencesB.allowsC.preventsD.causes8.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential informationA. Geographic isolation is sometimes but not always the reason for the creation of reproductive barriers between a parent population and the populations descended from itB. Genetic changes in a geographical isolated population do not necessarily make the population look different enough from its parent population to be considered a new speciesC. Geographical isolation allows the separated populations to evolve independently of each other and so can lead to the formation of new speciesD. Geographic isolation can lead to new species only if the gene pool of the isolated population changes enough to prevent it from reproducing with the parent population 9.According to paragraph 4, why does the size of a population affect the likelihood of allopatric speciation?A. Because smaller populations are more likely than larger ones to become geographically isolatedB. Because the gene pool of a small isolated population is more likely to undergo substantial change than is the gene pool of a larger populationC. Because a isolated population can become a new species with substantially less change to its gene pool than would be required by a larger populationD. Because smaller populations are more likely to be made up of stray animals or plants than larger populations are10.The word “managed” in the passage is closest in meaning toA.were ableB.were forcedC.arrivedD.expandedparagraph 5When oceanic islands are far enough apart to permit populations to evolve in isolation, butclose enough to allow occasional dispersions to occur, they are effectively outdoor laboratories of evolution. The Galapagos island chain is one of the world s greatest showcases of evolution Each island was born from underwater volcanoes and was gradually covered by organisms derived from strays that rode the ocean currents and winds from other islands and continents. Organisms can also be carried to islands by other organisms, such as sea birds that travel long distances with seeds clinging to their feathers.11.Paragraph 5 supports the idea that the Galapagos island chain was able to become “one of the world's greatest showcases of evolution” primarily because ofA. the richness of the volcanic soil of each of the islands in the chainB. the distance of the individual islands from each other and from the mainlandC. the relativity long time it took for the islands to become covered by organismsD. the outdoor laboratories that scientists have built on the islands to study evolutionparagraph 6The species on the Galapagos Islands today, most of which occur nowhere else, descended from organisms that floated, flew, or were blown over the sea from the South American mainland For instance, the Galapagos island chain has a total of thirteen species of closely related birds called Galapagos finches These birds have many similarities but differ in their feeding habits and their beak type, which is correlated with what they eat Accumulated evidence indicates that all thirteen finch species evolved from a single small population of ancestral birds that colonized one of the islands. Completely isolated on the island after migrating from the mainland, the founder population may have undergone significant changes in its gene pool and become a new species. Later, a few individuals of this new species may have been blown by storms to a neighboring island. Isolated on this second island, the second founder population could have evolved into a second new species, which could later recolonize the island from which its founding population emigrated. Today each Galapagos island has multiple species of finches, with as many as ten on some islands.12.According to paragraph 6. what is true about the thirteen species of Galapagos finches?A. All thirteen species are now found on most of the Galapagos IslandsB. All thirteen species are descended from the same population of ancestral birdsC. All thirteen species evolved on the island that was originally colonized by finches from the mainland.D. All thirteen species occur only in small, completely isolated populations.13.Look at the four squares [■] that indicate where the following sentence could be added to the passage.This process of speciation and colonization could have been repeated over and over again, gradually involving all the islands in the chain.The species on the Galapagos Islands today, most of which occur nowhere else, descended from organisms that floated, flew, or were blown over the sea from the South American mainland For instance, the Galapagos island chain has a total of thirteen species of closely related birds called Galapagos finches These birds have many similarities but differ in their feeding habits and their beak type, which iscorrelated with what they eat Accumulated evidence indicates that all thirteen finch species evolved from a single small population of ancestral birds that colonized one of the pletely isolated on the island after migrating from the mainland, the founder population may have undergone significant changes in its gene pool and become a new species. [■] Later, a few individuals of this new species may have been blown by storms to a neighboring island. [■]Isolated on this second island, the second founder population could have evolved into a second new species, which could later recolonize the island from which its founding population emigrated.[■]Today each Galapagos island has multiple species of finches, with as many as ten on some islands.[■]14.Directions：An introductory sentence for a brief summary of the passage is provided plete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage.The geographic isolation of a population can result in the rise of a new species. Answer ChoicesA.Isolation can result when a geographic barrier forms and splits a population or when a few organisms somehow get carried across an existing geographic barrier and form a new populationB.Speciation is more likely when an isolated population is small because significant genetic changes are more likely to occur in a small population than in a large oneC.Because of the geographic isolation of the Galapagos Islands, the species that now inhabit them have gene pools that have not changed very much since the islands were first populated.D.Fish populations are more easily isolated by geographic barriers than are populations of most other organisms because fish cannot move across areas where there is no water.E.The Galapagos Islands are well situated for speciation because they provide opportunities for population isolation while also making occasional dispersions between islands possible.F.Evidence indicates that the first organisms to reach the Galapagos Islands were probably a small population of finches that,in less than two million years of isolation,evolved into thirteen species.Explaining Dinosaur ExtinctionDinosaurs rapidly became extinct about 65 million years ago as part of a mass extinction known as the K-T event, because it is associated with a geological signature known as the K-T boundary, usually a thin band of sedimentation found in various parts of the world (K is the traditional abbreviation for the Cretaceous, derived from the German name Kreidezeit). Many explanations have been proposed for why dinosaurs became extinct. For example, some have blamed dinosaur extinction on the development of flowering plants, which were supposedly more difficult to digest and could have caused constipation or indigestion—except that flowering plants first evolved in the Early Cretaceous, about 60 million years before the dinosaurs died out. In fact, several scientists have suggested that the duckbill dinosaurs and homed dinosaurs, with their complex battery of grinding teeth, evolved to exploit this new resource of rapidly growing flowering plants Others have blamed extinction on competition from the mammals, which allegedly ate all the dinosaur eggs—except that mammals and dinosaurs appeared at the same time in the Late Triassic, about 190 million years ago, and there is no reason to believe that mammals suddenly acquired a taste for dinosaur eggs after 120 million years of coexistence Some explanations (such as the one stating that dinosaurs all died of diseases) fail because there is no way to scientifically test them, and they cannot move beyond the realm of speculation and guesswork.This focus on explaining dinosaur extinction misses an important point the extinction at the end of the Cretaceous was a global event that killed off organisms up and down the food chain. It wiped out many kinds of plankton in the ocean and many marine organisms that lived on the plankton at the base of the food chain. These included a variety of clams and snails, and especially the ammonites, a group of shelled squidlike creatures that dominated the Mesozoic seas and had survived many previous mass extinctions. The K-T event marked the end of the marine reptiles, suchas the mosasaurs and the plesiosaurs, which were the largest creatures that had ever lived in the seas and which ruled the seas long before whales evolved. On land, there was also a crisis among the land plants, in addition to the disappearance of dinosaurs. So any event that can explain the destruction of the base of the food chain (plankton in the ocean, plants on land) can better explain what happened to organisms at the top of the food chain, such as the dinosaurs. By contrast, any explanation that focuses strictly on the dinosaurs completely misses the point The Cretaceous extinctions were a global phenomenon, and dinosaurs were just a part of a bigger picture.According to one theory, the Age of Dinosaurs ended suddenly 65 million years ago when a giant rock from space plummeted to Earth. Estimated to be ten to fifteen kilometers in diameter, this bolide (either a comet or an asteroid) was traveling at cosmic speeds of 20-70 kilometers per second, or 45,000-156,000 miles per hour. Such a huge mass traveling at such tremendous speeds carries an enormous amount of energy. When the bolide struck this energy was released and generated a huge shock wave that leveled everything for thousands of kilometers around the impact and caused most of the landscape to burst into flames. The bolide struck an area of the Yucatan Peninsula of Mexico known as Chicxulub, excavating a crater 15-20 kilometers deep and at least 170 kilometers in diameter. The impact displaced huge volumes of seawater, causing much flood damage in the Caribbean. Meanwhile, the bolide itself excavated 100 cubic kilometers of rock and debris from the site, which rose to an altitude of 100 kilometers. Most of it fell back immediately, but some of it remained as dust in the atmosphere for months. This material, along with the smoke from the fires,shrouded Earth, creating a form of nuclear winter. According to computerized climate models, global temperatures fell to near the freezing point, photosynthesis halted, and most plants on land and in the sea died. With the bottom of the food chain destroyed, dinosaurs could not survive.paragraph 1Dinosaurs rapidly became extinct about 65 million years ago as part of a mass extinction known as the K-T event, because it is associated with a geologicalsignature known as the K-T boundary, usually a thin band of sedimentation found in various parts of the world (K is the traditional abbreviation for the Cretaceous, derived from the German name Kreidezeit). Many explanations have been proposed for why dinosaurs became extinct. For example, some have blamed dinosaur extinction on the development of flowering plants, which were supposedly more difficult to digest and could have caused constipation or indigestion—except that flowering plants first evolved in the Early Cretaceous, about 60 million years before the dinosaurs died out. In fact, several scientists have suggested that the duckbill dinosaurs and homed dinosaurs, with their complex battery of grinding teeth, evolved to exploit this new resource of rapidly growing flowering plants Others have blamed extinction on competition from the mammals, which allegedly ate all the dinosaur eggs—except that mammals and dinosaurs appeared at the same time in the Late Triassic, about 190 million years ago, and there is no reason to believe that mammals suddenly acquired a taste for dinosaur eggs after 120 million years of coexistence Some explanations (such as the one stating that dinosaurs all died of diseases) fail because there is no way to scientifically test them, and they cannot move beyond the realm of speculation and guesswork.1. In paragraph 1, why does the author include a discussion of when flowering plants evolved?A. To help explain why some scientists believe that the development of flowering plants led to dinosaur extinctionB. To cast doubt on the theory that the development of flowering plants caused dinosaurs to become extinctC. To suggest that dinosaurs were able to survive for as long as they did because of the availability of flowering plantsD. To emphasize that duckbill dinosaurs and horned dinosaurs were the first dinosaurs to become extinct2. The word “allegedly” in the passage is closest in meaning toA. inevitablyB. graduallyC. SupposedlyD. Increasingly3. According to paragraph 1 the extinction of the dinosaurs is unlikely to have been the result of competition from mammals becauseA. mammals would not have been capable of eating dinosaur eggsB. mammals did not appear in any significant numbers until after the Late TriassicC. mammals and dinosaurs did not, in fact, compete for any of the same resourcesD. mammals and dinosaurs lived together for roughly 120 million years before the extinctionparagraph 2This focus on explaining dinosaur extinction misses an important point the extinction at the end of the Cretaceous was a global event that killed off organisms up and down the food chain. It wiped out many kinds of plankton in the ocean and many marine organisms that lived on the plankton at the base of the food chain. These included a variety of clams and snails, and especially the ammonites, a group of shelled squidlike creatures that dominated the Mesozoic seas and had survived many previous mass extinctions. The K-T event marked the end of the marine reptiles, such as the mosasaurs and the plesiosaurs, which were the largest creatures that had ever lived in the seas and which ruled the seas long before whales evolved. On land, there was also a crisis among the land plants, in addition to the disappearance of dinosaurs. So any event that can explain the destruction of the base of the food chain (plankton in the ocean, plants on land) can better explain what happened to organisms at the top of the food chain, such as the dinosaurs. By contrast, any explanation that focuses strictly on the dinosaurs completely misses the point The Cretaceous extinctions were a global phenomenon, and dinosaurs were just a part of a bigger picture.paragraph 3According to one theory, the Age of Dinosaurs ended suddenly 65 million years ago when a giant rock from space plummeted to Earth. Estimated to be ten to fifteen kilometers in diameter, this bolide (either a comet or an asteroid) was traveling at cosmic speeds of 20-70 kilometers per second, or 45,000-156,000 miles per hour. Such a huge mass traveling at such tremendous speeds carries an enormous amount ofenergy. When the bolide struck this energy was released and generated a huge shock wave that leveled everything for thousands of kilometers around the impact and caused most of the landscape to burst into flames. The bolide struck an area of the Yucatan Peninsula of Mexico known as Chicxulub, excavating a crater 15-20 kilometers deep and at least 170 kilometers in diameter. The impact displaced huge volumes of seawater, causing much flood damage in the Caribbean. Meanwhile, the bolide itself excavated 100 cubic kilometers of rock and debris from the site, which rose to an altitude of 100 kilometers. Most of it fell back immediately, but some of it remained as dust in the atmosphere for months. This material, along with the smoke from the fires, shrouded Earth, creating a form of nuclear winter. According to computerized climate models, global temperatures fell to near the freezing point, photosynthesis halted, and most plants on land and in the sea died. With the bottom of the food chain destroyed, dinosaurs could not survive.4. According to paragraph 2, what is problematic about some scientists' focus on dinosaur extinction?A. Dinosaurs became extinct so long ago that no theory about their disappearance can be proven scientifically.B. Dinosaurs were not the only organisms that went extinct at the end of the Cretaceous period.C. More marine organisms went extinct during the Cretaceous than did dinosaur species.D. It is more important to understand how plankton and other marine organisms came to thrive during the Cretaceous period.5. According to paragraph 2, each of the following became extinct during the K-T event EXCEPTA. early species of whalesB. marine reptilesC. various species of clamsD. many species of land plants6. What makes the extinction of “the ammonites” especially significant?A. They were among the largest creatures that ever lived.。

托福阅读tpo42-1WORD打印 Explaining Dinosaur Extinction

Explaining Dinosaur ExtinctionDinosaurs rapidly became extinct about 65 million years ago as part of a mass extinction known as the K–T event, because it is associated with a geological signature known as the K–T boundary, usually a thin band of sedimentation found in various parts of the world (K is the traditional abbreviation for the Cretaceous, derived from the German name Kreidezeit). []Many explanations have been proposed for why dinosaurs became extinct.[] For example, some have blamed dinosaur extinction on the development of flowering plants, which were supposedly more difficult to digest and could have caused constipation or indigestion-except that flowering plants first evolved in the Early Cretaceous, about 60 million years before the dinosaurs died out.[] In fact, several scientists have suggested that the duckbill dinosaurs and horned dinosaurs, with their complex battery of grinding teeth, evolved to exploit this new resource of rapidly growing flowering plants.[] Others have blamed extinction on competition from the mammals, which allegedly ate all the dinosaur eggs-except that mammals and dinosaurs appeared at the same time in the Late Triassic, about 190 million years ago, and there is no reason to believe that mammals suddenly acquired a taste for dinosaur eggs after 120 million years of coexistence. Some explanations (such as the one stating that dinosaurs all died of diseases) fail because there is no way to scientifically test them, and they cannot move beyond the realm of speculation and guesswork.In paragraph 1, why does the author include a discussion of when flowering plants evolved?∙To help explain why some scientists believe that the development of flowering plants led to dinosaur extinction∙To cast doubt on the theory that the development of flowering plants caused dinosaurs to become extinct∙To suggest that dinosaurs were able to survive for as long as they did because of the availability of flowering plants∙To emphasize that duckbill dinosaurs and horned dinosaurs were the first dinosaurs to become extinctThe word "allegedly" in the passage is closest in meaning to∙inevitably∙gradually∙supposedly∙increasinglyAccording to paragraph 1, the extinction of the dinosaurs is unlikely to have been the result of competition from mammals because∙mammals would not have been capable of eating dinosaur eggs∙mammals did not appear in any significant numbers until after the Late Triassic∙mammals and dinosaurs did not, in fact, compete for any of the same resources∙mammals and dinosaurs lived together for roughly 120 million years before the extinction This focus on explaining dinosaur extinction misses an important point: the extinction at the end of the Cretaceous was a global event that killed off organisms up and down the food chain. It wiped out many kinds of plankton in the ocean and many marine organisms that lived on the plankton at the base of the food chain. These included a variety of clams and snails, and especially the ammonites, a group of shelled squidlike creatures that dominated the Mesozoic seas and had survived many previous mass extinctions. The K–T event marked the end of the marine reptiles, such as the mosasaurs and the plesiosaurs, which were the largest creatures that had ever lived in the seas and which ruled the seas long before whales evolved. On land, there was also a crisis among the land plants, in addition to the disappearance of dinosaurs. So any event that can explain the destruction of the base of the food chain (plankton in the ocean, plants on land) can better explain what happened to organisms at the top of the food chain, such as the dinosaurs. By contrast, any explanation that focuses strictly on the dinosaurs completely misses the point. The Cretaceous extinctions were a global phenomenon, and dinosaurs were just a part of a bigger picture.According to paragraph 2, what is problematic about some scientists' focus on dinosaur extinction?∙Dinosaurs became extinct so long ago that no theory about their disappearance can be proven scientifically.∙Dinosaurs were not the only organisms that went extinct at the end of the Cretaceous period.∙More marine organisms went extinct during the Cretaceous than did dinosaur species.∙It is more important to understand how plankton and other marine organisms came to thrive during the Cretaceous period.According to paragraph 2, each of the following became extinct during the K–T event EXCEPT∙early species of whales∙marine reptiles∙various species of clams∙many species of land plantsWhat makes the extinction of "the ammonites" especially significant?∙They were among the largest creatures that ever lived.∙They existed at the lowest level of the food chain.∙They had been able to survive in the Mesozoic seas.∙They had survived many previous mass extinctions.According to one theory, the Age of Dinosaurs ended suddenly 65 million years ago when a giant rock from space plummeted to Earth. Estimated to be ten to fifteen kilometers in diameter, this bolide (either a comet or an asteroid) was traveling at cosmic speeds of 20–70 kilometers per second, or 45,000–156,000 miles per hour. Such a huge mass traveling at such tremendous speeds carries an enormous amount of energy. When the bolide struck, this energy was released and generated a huge shock wave that leveled everything for thousands of kilometers around the impact and caused most of the landscape to burst into flames. The bolide struck an area of the Yucatán Peninsula of Mexico known as Chicxulub, excavating a crater 15–20 kilometers deep and at least 170 kilometers in diameter. The impact displaced huge volumes of seawater, causing much flood damage in the Caribbean. Meanwhile, the bolide itself excavated 100 cubic kilometers of rock and debris from the site, which rose to an altitude of 100 kilometers. Most of it fell back immediately, but some of it remained as dust in the atmosphere for months. This material, along with the smoke from the fires, shrouded Earth, creating a form of nuclear winter. According to computerized climate models, global temperatures fell to near the freezing point, photosynthesis halted, and most plants on land and in the sea died. With the bottom of the food chain destroyed, dinosaurs could not survive.How does paragraph 3 relate to paragraph 2?∙Paragraph 3 provides an alternative explanation to the one provided in paragraph 2.∙Paragraph 3 provides an explanation that satisfies the conditions set forth in paragraph 2.∙Paragraph 3 provides the facts to support the theory presented in paragraph 2.∙Paragraph 3 presents a theory that calls into question the position described in paragraph2.Paragraph 3 strongly suggests that if the bolide impact theory is correct, the majority of the extinctions associated with the K–T event resulted from∙sunlight being blocked for months by dust and smoke in Earth's atmosphere∙widespread flooding that followed the displacement of huge volumes of seawater∙the leveling of the landscape by the shock wave that was generated when the bolide struck Earth∙the rise in global temperatures caused by the fires that burned much of the landscapeLook at the four squares [] that indicate where the following sentence could be added to the passage.Some explanations seem plausible until the facts are considered.Drag your answer choices to the spaces where they belong. To remove an answer choice, click on it.To review the passage, click VIEW TEXT.Over the years, scientists have proposed a number of theories as to why dinosaurs suddenly became extinct about 65 million years ago.∙∙∙Answer ChoicesA. Many explanations for dinosaur extinction have been proposed, but most ofthem are either called into question by known facts or are merely unsupported hypotheses.B. Although mammals and dinosaurs appeared at about the same time in theLate Triassic, the K–T event, which marked the end of the dinosaurs, apparently had relatively little impact on mammals.C.Focusing on dinosaurs misses the point that the extinction, at about thesame time, of the shelled squidlike creatures that dominated the Mesozoic seas was far more scientifically significant.D. Any satisfactory explanation of the mass extinction of dinosaurs must takeinto account the fact that the disappearance of the dinosaurs was part of a global mass extinction.puterized climate models of global temperature fluctuations supportthe theory that a huge rock from space hit the Yucatan Peninsula in Mexico about 65 million years ago.F. A huge bolide striking Earth would have created conditions in which mostplants would have died, thus explaining the mass extinction of organisms—including dinosaurs—further up the food chain.。

托福TPO42口语Task4阅读文本+听力文本+题目+满分范文

为了帮助大家高效备考托福，为大家带来托福TPO42口语Task4阅读文本+听力文本+题目+满分范文，希望对大家备考有所帮助。

托福TPO42口语Task4阅读文本： Habituation Habituation is a form of learning that is quite common among animals. When an animal experiences a situation for the first time, particularly one it considers threatening, it may instinctively respond by running away or by warning other members of its community with alarm calls. Normally, it responds this way each time the situation occurs. However, if through continuous and prolonged exposure the animal learns that the situation is harmless, the behavior gradually diminishes. Ultimately, it will stop responding to the situation altogether. Thus, through habituation a natural or instinctive behavior gradually changes. 托福TPO42口语Task4听力文本： Now listen to part of a lecture in a biology class. Prairie dogs are small animals you're likely to find on wide, relatively flat, grassy areas of land in North America. They tend to live together in large numbers. Now, generally these animals don't come into contact with human beings, but every now and then, they do. So let's assume that some prairie dogs happen to live in an area where human beings frequently come and go. Now the first time the animals would see a human being, they'd instinctively react by making a sharp barking sound like a dog and jumping up and down, essentially warning or alerting other prairie dogs that are nearby of this potential threat, exactly the same way they'd react if they came upon or were threatened by a snake or a hawk, an animal that preys on them. Their instinctive reaction would be one of fear. They'd keep an eye on the human beings until these scary, possibly threatening individuals are gone. And...they're likely to react this way every time they see a human being. However, if people pass through the area day after day without threatening them or trying to harm them, well, it turns out that the prairie dogs will gradually stop barking and jumping up and down when they see a human being passing through the area. At some point, they'd stop reacting to humans as though they were a threat. 托福TPO42口语Task4题目： Explain how the example of the prairie dog illustrates the concept of habituation. 托福TPO42口语Task4满分范文： In the lecture, the professor mainly talked about the theory that through habituation a natural behavior gradually changes. To reinforce the theory, the professor gave an example in his speech. That is, assume prairie dogs live in an area where human beings frequently come and go. The first time the animals see a person, they’d react by barking like a dog and jumping up and down instinctively to warn or alert other prairie dogs nearby, they’d do the same to the animal that preys on them, such as a snake or a hawk. This kind of reaction is out of their fear. And they’d keep an eye on the human beings until these possible threatening individuals are gone. However, if people pass through the area day by day without hurting them, then the prairie dogs will gradually stop barking and jumping up and down when they see a person passing through the area, they’d stop reacting to humans as a threat. And that's the example the speaker presented to explain his idea. 以上是给大家整理的托福TPO42口语Task4阅读文本+听力文本+题目+满分范文，希望对你有所帮助!。

tpo42三篇托福阅读TOEFL原文译文题目答案译文背景知识

tpo42三篇托福阅读TOEFL原文译文题目答案译文背景知识阅读-1 (2)原文 (2)译文 (5)题目 (8)答案 (18)背景知识 (18)阅读-2 (24)原文 (24)译文 (27)题目 (30)答案 (39)背景知识 (39)阅读-3 (41)原文 (41)译文 (44)题目 (47)答案 (55)背景知识 (55)阅读-1原文Geographic Isolation Of Species①Biologist Ernst Mayr defined a species as “an actually or potentially interbreeding population that does not interbreed with other such populations when there is opportunity to do so.”A key event in the origin of many species is the separation of a population with its gene pool (all of the genes in a population at any one time) from other populations of the same species, thereby preventing population interbreeding. With its gene pool isolated, a separate population can follow its own evolutionary course. In the formation of many species, the initial isolation of a population seems to have been a geographic barrier. This mode of evolving new species is called allopatric speciation.②Many factors can isolate a population geographically. A mountain range may emerge and gradually split a population of organisms that can inhabit only lowland lakes, certain fish populations might become isolated in this way. Similarly, a creeping glacier may gradually divide a population, or a land bridge such as the Isthmus of Panama may form and separate the marine life in the ocean waters on either side.③How formidable must a geographic barrier be to keep populations apart? It depends on the ability of the organisms to move across barriers. Birds and coyotes can easily cross mountains and rivers. The passage of wind-blown tree pollen is also not hindered by such barriers, and the seeds of many plants may be carried back and forth on animals. In contrast, small rodents may find a deep canyon or a wide river an effective barrier. For example, the Grand Canyon, in the southwestern United States, separate the range of the white-tailed antelope squirrel from that of the closely related Harris’antelope squirrel. Smaller, with a shorter tail that is white underneath, the white-tailed antelope squirrel inhabits deserts north of the canyon and west of the Colorado River in southern California. Harris' antelope squirrel has a more limited range in deserts south of the Grand Canyon.④Geographic isolation creates opportunities for new species to develop, but it does not necessarily lead to new species because speciation occurs only when the gene pool undergoes enough changes to establish reproductive barriers between the isolated population and its parent population. The likelihood of allopatric speciation increases when a population is small as well as isolated, making it more likely than a large population to have its gene pool changed substantially. For example, in less than two million years, small populations of stray animals and plants from the South American mainland that managedto colonize the Galapagos Islands gave rise to all the species that now inhabit the islands.⑤When oceanic islands are far enough apart to permit populations to evolve in isolation, but close enough to allow occasional dispersions to occur, they are effectively outdoor laboratories of evolution. The Galapagos island chain is one of the world's greatest showcases of evolution. Each island was born from underwater volcanoes and was gradually covered by organisms derived from strays that rode the ocean currents and winds from other islands and continents. Organisms can also be carried to islands by other organisms, such as sea birds that travel long distances with seeds clinging to their feathers.⑥The species on the Galapagos Islands today, most of which occur nowhere else, descended from organisms that floated, flew, or were blown over the sea from the South American mainland. For instance, the Galapagos island chain has a total of thirteen species of closely related birds called Galapagos finches. These birds have many similarities but differ in their feeding habits and their beak type, which is correlated with what they eat. Accumulated evidence indicates that all thirteen finch species evolved from a single small population of ancestral birds that colonized one of the islands. Completely isolatedon the island after migrating from the mainland, the founder population may have undergone significant changes in its gene pool and become a new species. Later, a few individuals of this new species may have been blown by storms to a neighboring island. Isolated on this second island, the second founder population could have evolved into a second new species, which could later recolonize the island from which its founding population emigrated. Today each Galapagos island has multiple species of finches, with as many as ten on some islands.译文物种的地理隔离①生物学家恩斯特·迈尔将物种定义为“实际上或潜在的杂交种群，在有机会的情况下不会与其他同类种群杂交。

TPO-42 阅读文本和对应题目文本第2篇

Explaining Dinosaur ExtinctionDinosaurs rapidly became extinct about 65 million years ago as part of a mass extinction known as the K-T event, because it is associated with a geological signature known as the K-T boundary, usually a thin band of sedimentation found in various parts of the world (K is the traditional abbreviation for the Cretaceous, derived from the German name Kreidezeit).Many explanations have been proposed for why dinosaurs became extinct. For example, some have blamed dinosaur extinction on the development of flowering plants, which were supposedly more difficult to digest and could have caused constipation or indigestion—except that flowering plants first evolved in the Early Cretaceous, about 60 million years before the dinosaurs died out. In fact, several scientists have suggested that the duckbill dinosaurs and homed dinosaurs, with their complex battery of grinding teeth, evolved to exploit this new resource of rapidly growing flowering plants Others have blamed extinction on competition from the mammals, which allegedly ate all the dinosaur eggs—except that mammals and dinosaurs appeared at the same time in the Late Triassic, about 190 million years ago, and there is no reason to believe that mammals suddenly acquired a taste for dinosaur eggs after 120 million years of coexistence Some explanations (such as the one stating that dinosaurs all died of diseases) fail because there is no way to scientifically test them, and they cannot move beyond the realm of speculation and guesswork.This focus on explaining dinosaur extinction misses an important point the extinction at the end of the Cretaceous was a global event that killed off organisms up and down the food chain. It wiped out many kinds of plankton in the ocean and many marine organisms that lived on the plankton at the base of the food chain. These included a variety of clams and snails, and especially the ammonites, a group of shelled squidlike creatures that dominated the Mesozoic seas and had survived many previous mass extinctions. The K-T event marked the end of the marine reptiles, such as the mosasaurs and the plesiosaurs, which were the largest creatures that had ever lived in the seas and which ruled the seas long before whales evolved. On land, there was also a crisis among the land plants, in addition to the disappearance of dinosaurs. So any event that can explain the destruction of the base of the food chain (plankton in the ocean, plants on land) can better explain what happened to organisms at the top of the food chain, such as the dinosaurs. By contrast, any explanation that focuses strictly on the dinosaurs completely misses the point The Cretaceous extinctions were a global phenomenon, and dinosaurs were just a part of a bigger picture.According to one theory, the Age of Dinosaurs ended suddenly 65 million years ago when a giant rock from space plummeted to Earth. Estimated to be ten to fifteen kilometers in diameter, this bolide (either a comet or an asteroid) was traveling at cosmic speeds of 20-70 kilometers per second, or 45,000-156,000 miles per hour. Such a huge mass traveling at such tremendous speeds carries an enormous amount of energy. When the bolide struck this energy was released and generated a huge shock wave that leveled everything for thousands of kilometers around the impact and caused most of the landscape to burst into flames. The bolide struck an area of the Yucatan Peninsula of Mexico known as Chicxulub, excavating a crater 15-20 kilometers deep and at least 170 kilometers in diameter. The impact displaced huge volumes of seawater, causing much flood damage in the Caribbean. Meanwhile, the bolide itself excavated 100 cubic kilometers of rock and debris from the site, which rose to an altitude of 100 kilometers. Most of it fell back immediately, but some of it remained as dust in the atmosphere for months. This material, along with the smoke from the fires,shrouded Earth, creating a form of nuclear winter. According to computerized climate models, global temperatures fell to near the freezing point, photosynthesis halted, and most plants on land and in the sea died. With the bottom of the food chain destroyed, dinosaurs could not survive.paragraph 1Dinosaurs rapidly became extinct about 65 million years ago as part of a mass extinction known as the K-T event, because it is associated with a geological signature known as the K-T boundary, usually a thin band of sedimentation found in various parts of the world (K is the traditional abbreviation for the Cretaceous, derived from the German name Kreidezeit).Many explanations have been proposed for why dinosaurs became extinct. For example, some have blamed dinosaur extinction on the development of flowering plants, which were supposedly more difficult to digest and could have caused constipation or indigestion—except that flowering plants first evolved in the Early Cretaceous, about 60 million years before the dinosaurs died out. In fact, several scientists have suggested that the duckbill dinosaurs and homed dinosaurs, with their complex battery of grinding teeth, evolved to exploit this new resource of rapidly growing flowering plants Others have blamed extinction on competition from the mammals, which allegedly ate all the dinosaur eggs—except that mammals and dinosaurs appeared at the same time in the Late Triassic, about 190 million years ago, and there is no reason to believe that mammals suddenly acquired a taste for dinosaur eggs after 120 million years of coexistence Some explanations (such as the one stating that dinosaurs all died of diseases) fail because there is no way to scientifically test them, and they cannot move beyond the realm of speculation and guesswork.1.In paragraph 1, why does the author include a discussion of when flowering plants evolved?A.To help explain why some scientists believe that the development of flowering plants led todinosaur extinctionB.To cast doubt on the theory that the development of flowering plants caused dinosaurs tobecome extinctC.To suggest that dinosaurs were able to survive for as long as they did because of the availabilityof flowering plantsD.To emphasize that duckbill dinosaurs and horned dinosaurs were the first dinosaurs to becomeextinct2.The word “allegedly” in the passage is closest in meaning toA.inevitablyB.graduallyC.SupposedlyD.Increasingly3.According to paragraph 1 the extinction of the dinosaurs is unlikely to have been the result of competition from mammals becauseA. mammals would not have been capable of eating dinosaur eggsB. mammals did not appear in any significant numbers until after the Late TriassicC. mammals and dinosaurs did not, in fact, compete for any of the same resourcesD. mammals and dinosaurs lived together for roughly 120 million years before the extinctionparagraph 2This focus on explaining dinosaur extinction misses an important point the extinction at the end of the Cretaceous was a global event that killed off organisms up and down the food chain. It wiped out many kinds of plankton in the ocean and many marine organisms that lived on the plankton at the base of the food chain. These included a variety of clams and snails, and especially the ammonites, a group of shelled squidlike creatures that dominated the Mesozoic seas and had survived many previous mass extinctions. The K-T event marked the end of the marine reptiles, such as the mosasaurs and the plesiosaurs, which were the largest creatures that had ever lived in the seas and which ruled the seas long before whales evolved. On land, there was also a crisis among the land plants, in addition to the disappearance of dinosaurs. So any event that can explain the destruction of the base of the food chain (plankton in the ocean, plants on land) can better explain what happened to organisms at the top of the food chain, such as the dinosaurs. By contrast, any explanation that focuses strictly on the dinosaurs completely misses the point The Cretaceous extinctions were a global phenomenon, and dinosaurs were just a part of a bigger picture.paragraph 3According to one theory, the Age of Dinosaurs ended suddenly 65 million years ago when a giant rock from space plummeted to Earth. Estimated to be ten to fifteen kilometers in diameter, this bolide (either a comet or an asteroid) was traveling at cosmic speeds of 20-70 kilometers per second, or 45,000-156,000 miles per hour. Such a huge mass traveling at such tremendous speeds carries an enormous amount of energy. When the bolide struck this energy was released and generated a huge shock wave that leveled everything for thousands of kilometers around the impact and caused most of the landscape to burst into flames. The bolide struck an area of the Yucatan Peninsula of Mexico known as Chicxulub, excavating a crater 15-20 kilometers deep and at least 170 kilometers in diameter. The impact displaced huge volumes of seawater, causing much flood damage in the Caribbean. Meanwhile, the bolide itself excavated 100 cubic kilometers of rock and debris from the site, which rose to an altitude of 100 kilometers. Most of it fell back immediately, but some of it remained as dust in the atmosphere for months. This material, along with the smoke from the fires, shrouded Earth, creating a form of nuclear winter. According to computerized climate models, global temperatures fell to near the freezing point, photosynthesis halted, and most plants on land and in the sea died. With the bottom of the food chain destroyed, dinosaurs could not survive.4. According to paragraph 2, what is problematic about some scientists' focus on dinosaur extinction?A. Dinosaurs became extinct so long ago that no theory about their disappearance can be proven scientifically.B. Dinosaurs were not the only organisms that went extinct at the end of the Cretaceous period.C. More marine organisms went extinct during the Cretaceous than did dinosaur species.D. It is more important to understand how plankton and other marine organisms came to thrive during the Cretaceous period.5. According to paragraph 2, each of the following became extinct during the K-T event EXCEPTA. early species of whalesB. marine reptilesC. various species of clamsD. many species of land plants6.What makes the extinction of “the ammonites” especially significant?A. They were among the largest creatures that ever lived.B. They existed at the lowest level of the food chain.C. They had been able to survive in the Mesozoic seas.D. They had survived many previous mass extinctions.7. The word “halted” in the passage is closest in meaning toA. slowedB. stoppedC. contractedD. declined8.The word “strictly" in the passage is closest in meaning toA. exclusivelyB. mainlyC. initiallyD. Wrongly9.The word “crisis” in the passage is closest in meaning toA. collapseB. disturbanceC. critical situationD. loss10. How does paragraph 3 relate to paragraph 2?A. Paragraph 3 provides an alternative explanation to the one provided in paragraph 2.B. Paragraph 3 provides an explanation that satisfies the conditions set forth in paragraph 2.C. Paragraph 3 provides the facts to support the theory presented in paragraph 2.D. Paragraph 3 presents a theory that calls into question the position described in paragraph 2.paragraph 3According to one theory, the Age of Dinosaurs ended suddenly 65 million years ago when a giant rock from space plummeted to Earth. Estimated to be ten to fifteen kilometers in diameter, this bolide (either a comet or an asteroid) was traveling at cosmic speeds of 20-70 kilometers per second, or 45,000-156,000 miles per hour. Such a huge mass traveling at such tremendous speeds carries an enormous amount of energy. When the bolide struck this energy was released and generated a huge shock wave that leveled everything for thousands of kilometers around the impact and caused most of the landscape to burst into flames. The bolide struck an area of the Yucatan Peninsula of Mexico known as Chicxulub, excavating a crater 15-20 kilometers deep and at least 170 kilometers in diameter. The impact displaced huge volumes of seawater, causing much flood damage in the Caribbean. Meanwhile, the bolide itself excavated 100 cubic kilometers of rock and debris from the site, which rose to an altitude of 100 kilometers. Most of it fell back immediately, but some of itremained as dust in the atmosphere for months. This material, along with the smoke from the fires, shrouded Earth, creating a form of nuclear winter. According to computerized climate models, global temperatures fell to near the freezing point, photosynthesis halted, and most plants on land and in the sea died. With the bottom of the food chain destroyed, dinosaurs could not survive.11.Paragraph 3 answers all of the following questions EXCEPT:A. Why did the bolide fall to Earth?B. How fast was the bolide traveling?C. How was the bolide capable of generating a shock wave?D. How did the bolide cause flood damage to the Caribbean?12.Paragraph 3 strongly suggests that if the bolide impact theory is correct, the majority of the extinctions associated with the K-T event resulted fromA. sunlight being blocked for months by dust and smoke in Earth's atmosphereB. widespread flooding that followed the displacement of huge volumes of seawaterC. the leveling of the landscape by the shock wave that was generated when the bolide struck EarthD. the rise in global temperatures caused by the fires that burned much of the landscape13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.Some explanations seem plausible until the facts are considered.Where would the sentence best fit? Click on a square [■] to add the sentence to the passage.Dinosaurs rapidly became extinct about 65 million years ago as part of a mass extinction known as the K-T event, because it is associated with a geological signature known as the K-T boundary, usually a thin band of sedimentation found in various parts of the world (K is the traditional abbreviation for the Cretaceous, derived from the German name Kreidezeit). [■] Many explanations have been proposed for why dinosaurs became extinct. [■] For example, some have blamed dinosaur extinction on the development of flowering plants, which were supposedly more difficult to digest and could have caused constipation or indigestion—except that flowering plants first evolved in the Early Cretaceous, about 60 million years before the dinosaurs died out. [■]In fact, several scientists have suggested that the duckbill dinosaurs and homed dinosaurs, with their complex battery of grinding teeth, evolved to exploit this new resource of rapidly growing flowering plants. [■]Others have blamed extinction on competition from the mammals, which allegedly ate all the dinosaur eggs—except that mammals and dinosaurs appeared at the same time in the Late Triassic, about 190 million years ago, and there is no reason to believe that mammals suddenly acquired a taste for dinosaur eggs after 120 million years of coexistence Some explanations (such as the one stating that dinosaurs all died of diseases) fail because there is no way to scientifically test them, and they cannot move beyond the realm of speculation and guesswork.14.Direction: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.Drag your answer choices to the spaces where they belong. To remove an answer choice, click on it.To review the passage, click VIEW TEXT.Over the years, scientists have proposed a number of theories as to why dinosaurs suddenly became extinct about 65 million years ago.Answer ChoicesA.Many explanations for dinosaur extinction have been proposed, but most of them are eithercalled into question by known facts or are merely unsupported hypotheses.B.Focusing on dinosaurs misses the point that the extinction, at about the same time, of the shelledsquidlike creatures that dominated the Mesozoic seas was far more scientifically significant.puterized climate models of global temperature fluctuations support the theory that a hugerock from space hit the Yucatan Peninsula in Mexico about 65 million years ago.D.Although mammals and dinosaurs appeared at about the same time in the Late Triassic, the K-Tevent, which marked the end of the dinosaurs, apparently had relatively little impact onmammals.E.Any satisfactory explanation of the mass extinction of dinosaurs must take into account the factthat the disappearance of the dinosaurs was part of a global mass extinction.F. A huge bolide striking Earth would have created conditions in which most plants would havedied, thus explaining the mass extinction of organisms—including dinosaurs—further up the food chain.。

托福TPO42阅读Passage1原文文本+题目+答案解析

为了帮助大家高效备考托福，为大家带来托福TPO42阅读Passage1原文文本+题目+答案解析，希望对大家备考有所帮助。

Geographic Isolation of Species Biologist Ernst Mayr defined a species as“an actually or potentially interbreeding population that does not interbreed with other such populations when there is opportunity to do so.”A key event in the origin of many species is the separation of a population with its gene pool(all of the genes in a population at any one time)from other populations of the same species,thereby preventing population interbreeding With its gene pool isolated,a separate population can follow its own evolutionary course.In the formation of many species,the initial isolation of a population seems to have been a geographic barrier This mode of evolving new species is called allopatric speciation. Many factors can isolate a population geographically.A mountain range may emerge and gradually split a population of organisms that can inhabit only lowland lakes,certain fish populations might become isolated in this way.Similarity,a creeping glacier may gradually divide a population,or a land bridge such as the Isthmus of Panama may form and separate the marine life in the ocean waters on either side. How formidable must a geographic barrier be to keep populations apart?It depends on the ability of the organisms to move across barriers.Birds and coyotes can easily cross mountains and rivers.The passage of wind-blown tree pollen is also not hindered by such barriers,and the seeds of many plants may be earned back and forth on animals In contrast,small rodents may find a deep canyon or a wide river an effective barrier.For example,the Grand Canyon,in the southwestern United Slates,separate the range of the while-tailed antelope squirrel from that of the closely related Harris’antelope squirrel.Smaller,with a shorter tail that is white underneath,the white-tailed antelope squirrel inhabits deserts north of the canyon and west of the Colorado River in southern California Hams'antelope squirrel has a more limited range in deserts south of the Grand Canyon. Geographic isolation creates opportunities for new species to develop,but it does not necessarily lead to new species because speciation occurs only when the gene pool undergoes enough changes to establish reproductive barriers between the isolated population and its parent population.The likelihood of allopatric speciation increases when a population is small as well as isolated,making it more likely than a large population to have its gene pool changed substantially.For example,in less than two million years,small populations of stray animals and plants from the South American mainland that managed to colonize the Galapagos Islands gave rise to all the species that now inhabit the islands. When oceanic islands are far enough apart to permit populations to evolve in isolation,but close enough to allow occasional dispersions to occur,they are effectively outdoor laboratories of evolution.The Galapagos island chain is one of the world s greatest showcases of evolution Each island was born from underwater volcanoes and was gradually covered by organisms derived from strays that rode the ocean currents and winds from other islands and anisms can also be carried to islands by other organisms,such as sea birds that travel long distances with seeds clinging to their feathers. The species on the Galapagos Islands today,most of which occur nowhere else,descended from organisms that floated,flew,or were blown over the sea from the South American mainland For instance,the Galapagos island chain has a total of thirteen species of closely related birds called Galapagos finches These birds have many similarities but differ in their feeding habits and their beak type,which is correlated with what they eat Accumulated evidence indicates that all thirteen finch species evolved from a single small population of ancestral birds that colonized one of the pletely isolated on the island after migrating from the mainland,the founder population may have undergone significant changes in its gene pool and become a new ter,a few individuals of this new species may have been blown by storms to a neighboring island.Isolated on this second island,the second founder population could have evolved into a second new species,which could later recolonize the island from which its founding population emigrated.Today each Galapagos island has multiple species of finches,with as many as ten on some islands. paragraph 1 Biologist Ernst Mayr defined a species as“an actually or potentially interbreeding population that does not interbreed with other such populations when there is opportunity to do so.”A key event in the origin of many species is the separation of a population with its gene pool(all of the genes in a population at any one time)from other populations of the same species,thereby preventing population interbreeding With its gene pool isolated,a separate population can follow its own evolutionary course.In the formation of many species,the initial isolation of a population seems to have been a geographic barrier This mode of evolving new species is called allopatric speciation. 1.The word“key”in the passage is closest in meaning to【词汇题】A.earlyB.crucialC.noticeableD.frequent 答案：B 解析：key,关键的。

TPO42综合写作听力文本宋克明

TPO42综合写作听力文本宋克明None of the solutions you've read about will effectively stop birds from getting injured.First, replacing regular glass with one-way glass. Well, the problem with one-way glass is that to the bird on the outside, a one-way glass surface reflects just like a mirror, and a surface that reflects like a mirror is just as bad as regular glass for birds because birds don’t understand the mirrors. If they see a reflection of the sky in a mirror or of a tree in a mirror, they'd think the reflection is the sky or is the tree. And they'll fly right into them.The second solution, painting colorful patterns like stripes on regular glass, also has problems. As the reading said, these designs include openings so people inside the buildings can see out, but birds will perceive these unpainted openings as open holes. And if birds think that they are seeing holes, they'll try to fly right through them. To prevent birds from doing this, the unpainted spaces in a window would have to be extremely small, but that would then make the rooms of the buildings too dark for the people inside them.The third solution, creating an artificial magnetic field,won't work very well either. While it’s true that birds use Earth's magnetic field to help them navigate, they use this only when they are travelling very long distances. For example, if a bird is migrating from a cold country to awarm one before winter, it will use its magnetic sense to figure out which way it should fly. But this ability isn't used to go over short distances, such as going from one side of the city to another. For short trips, birds use their eyes and the brightness of light to determine where to go. So magnetic signals from buildings won’t have much effect.。