托福TPO29阅读Passage2原文文本+题目+答案解析
TPO 29 托福综合写作+独立写作范文
TPO 29综合写作：阅读：ed会向南迁徙，因为恶略的天气环境阅读1：去南方找食物，NS比较寒冷，没法生存听力1：NS much warmer than today.夏天能提供足够的食物，24消失的阳光共植物生长冬天也有食物，dead plants 也能能够提供足够的营养阅读2：发现恐龙是群居的，有助于迁徙听力2：群居并不意味着迁徙，有其他的好处：可以保护自己免受捕食者的侵略例子：elk 群居，但是他们不迁徙阅读3：身体条件上有能力迁徙比较长的距离，寒冷的地方到温暖的地方听力3：青年恐龙身体条件上无法迁徙，跟不上群体，成年的也不会把他们落下，不能自给自足，群体都会呆在NS，不迁徙In the reading passage, the writer claim that edmontosaurus had to migrate to hospitable places in the south, if they want to survive in the cold weather. The speaker, however, contradicts this view for the following three reasons.First of all, the reading materials points out that it is difficult that edmontosaurus to find food in cold winter because of they were fed on plants exclusively. But the speaker reputes that warm weather in summer supplied perfect condition for plants to grow. So edmontosaurus might found lots of nutritious dead vegetation around in the winter, which made migration unnecessary.Second, unearthed skeletons from the same site indicated that edmontosaurus lived in herds. Living in herds made migration much easy. But the lecture gave an example of Roosevelt elks to prove that group living might have various types of reasons. So edmontosaurus may live in herds in order to seek for extra protection. So living in herds could not provide evidence for migration claim.Lastly, edmontosaurus, in view of the writer, had the ability of long-distance movement. Although the lecturer admitted the locomotive capability of edmontosaurus, he points out that juvenile edmontosaurus were lack of such ability. So the herd would not leave juveniles behind in the North Slope, which strongly reputes the author’s claim.独立写作：Do you agree or disagree with the following statement? To improve the quality of education, universities should spend more money on salaries for university professors. Use specific reasons and examples to support your answer.With the rapid development of society, more and more elites are required for advance science and technology. So how to improve the quality of higher education becomes an emergency problem for universities. Improve the facilities and equipments, design attracting courses, introducing famous professors, elevate salaries for professors or provide more resources for students like holding international communicating meetings, all these strategies will solve the problem. So I think universities should prefer to taking multiple methods to improve the quality of education rather than just spending money on professors.As a boost enrollment in universities nowadays, there are so many students attend college that will require more funding and resource. Universities should employ more faculties, purchase more facilities to cope with the increase population in campus. Only that happens that every student will get equal chance to gain knowledge and share the colorful campus life. For instance, when I was a fresh student in my college, owing to so many students want to study in library that I need get up early and rush the way to get a seat. Limited seats in the library influences students' study passion which leads to the decline of the quality of education in the end. So I think the most important thing to improve quality of education is to make the facilities prefect.What's more, universities should hold some international communicating meetings andintroduce professors who are talented, knowledgeable and prestigious. So students can have more opportunities to share the advanced achievements directly and communicate with the professors who are famous in their interested field. I think that will inspire students' creativity, intelligence and imagination which need in the college study, then they will contribute more to the university and the society.Admittedly, universities should increase the salaries for professors. A college teacher is more responsible for the quality of education because college life maybe the last stage of students' study period before taking a job. What can a student do depend on what knowledge and skills they gained from school and from professors. So professors will be more dedicated to their work with high pay which lead to more useful people graduate from school.All in all, if universities have enough money they should take variety ways to improve the quality of education, especially what I mentioned above.。
托福模拟试卷29(题后含答案及解析)
托福模拟试卷29(题后含答案及解析)题型有：1. Listening Comprehension 3. Reading Comprehension 4. SPEAKING 5. WRITINGSection One：Listening Comprehension听力原文：S I need to buy a pass for the university swimming pool. Can I do that here?E You sure can. Have you ever had a pass before?S No, I’m a freshman. This is actually my first semester at the university.E OK. Well, I’m going to need to see your student ID card and the passes are twenty-five dollars a month. We accept cash, credit cards, and personal checks. How would you like to pay?S Nothing fancy, I’m afraid. I’ve only got regular old money. But, that seems sort of expensive. How often can I use the pass in one month? Every day?E The pool is closed to the public on Tuesdays, because that’s when the swim team uses it for training. We call those purple days. And there are some other times when access is restricted to certain members of the university community.S Oh. How do I know when I can use the pool?E See the calendar over there on the wall? The pool is open to the public on all the days marked in blue. Any day that’s marked in red means that the university faculty can use the pool for free, but everyone else still has to pay.S What about the days that are yellow?I can see a few of those, too.E Yellow means that the pool is closed for maintenance and cleaning. No one can swim on those days. But there are only one or two of those a month, so it’s never really been a problem.S The calendar seems to be full of blue days, so I guess the pass is a good idea. I can get a lot of use out of it. But, is it possible to just pay each time I go? Maybe that will be cheaper.E You can buy single-entry passes, but they are almost five dollars each. So, if you plan on going more than five times a month, it’s better to get the monthly pass.S I’ll probably try to go swimming at least three times a week. Thanks for your help.In this part of the section, you will hear 1 conversation and 2 lectures. You must answer each question. After you answer, click the Next icon. Then click the OK icon to confirm your answer and go on to the next question. After you click the OK icon, you will not be able to return to previous questions. You will now begin this part of the Listening section. You will have 10 minutes to answer the questions.1．What does the student want to do?A．Purchase a pass.B．Pay tuition fees.C．Check times and dates.D．Sign up for classes.正确答案：A解析：目的题学生说的第一句话是”我要办一张校游泳馆的游泳卡”。
tpo29阅读答案
tpo29阅读答案【篇一：tpo29阅读文本】racteristics of roman potterythe pottery of ancient romans is remarkable in several ways. the high quality of roman pottery is very easy to appreciate when handling actual pieces of table ware or indeed kitchenware and amphorae(the large jars used throughout the mediterranean for the transport and storage of liquids, such as wine and oil). however, it is impossible to do justice to roman wares on the page, even when words can be backed up by photographs and drawings. most roman pottery is light and smooth to the touch and very tough, although, like all pottery, it shatters if dropped on a hard surface. it is generall made with carefully selected and porified clay, worked to thin-walled and standardized shapes on a fast wheel and fired in akiln(pottery oven) capable of ensuring a consistent finish. with handmade pottery, inevitably there are slight differences between individual vessels of the same desigh andoccasional minor blemishe(flaws). but what strikes the eye and the touch most immediately and most powerfully with roman pottery is its consistent high quality.le it, they often comment on how modern it looks and feels, and they need to be convinced of its true age.as impressive as the quality of roman pottery is its sheer massive quantity. when considering quantities, we would ideally like to havesome estimates for overall production from particular sites of pottery manufacture and for overall consumption at specific settlements. unfortunately, it is in the nature of the archaeological evidence, which is almost in variably only a sample of what once existed, that such figures will always be elusive. however, no one who has ever worked in the field would quenstion the abundance of roman pottery, particularly in the mediterranean region. this abundance is notable in roman settlements(especially urban sites)where the labor that archaeologists have to put into the washing and sorting of potsherds (fragments of pottery) constitutes a high proportion of the total work during the initial phases of excavation.■only rarely can we derive any “real” quantities from deposits of broken pots. ■however, there is one exceptional dump, which does represent a very large part of the site’s total history of consumption and for which an estimate of quantity has been produced. ■on the left bankof the tiber river in rome, by one of the river ports of the ancient city, is a substantial hill some 50 meters high called monte testaccio. ■ it is made up entirely of broke oil amphorae,mainly of the second and third centuries a.d. it has been estimated that monte testaccil contains the remains of some 53 million amphorae, in which aroud 6,000 million liters of oil were imported into the city from overseas. imports into imperial rome were supported by the full might of the state and were therefore quite exceptional—but the size of the operations at monte testaccil, and the productivity and complexity that lay behind them, nonetheless cannot fail to impress. this was a society with similarities to modern ones—moving good s on a gigantic scale, manufacturing high-quality containers to do so, and occasionally, as here, even discarding them on delivery.q1 paragraph 1 indicates which of the following about roman pottery?a. roman amphorae were of much higher quality overall than other roman pottery.b. roman pottery can best be appreciated when actual pieces are handled.c. roman pottery declined slightly in quality when the use of fast wheels and kilns was introduced.d. roman practical tableware spread more rapidly across the mediterranean than amphorae did.paragraph 1 is marked with an arrowq2 all of the following are mentioned in paragraph 1 as characteristics of roman pottery except:a. it was usually made with high-quality clay.b. it generally did not weigh much.c. it did not break as easily as other ancient pottery.d. it sometimes had imperfections.【篇二：托福阅读tpo29(试题答案译文)第3篇-the history of waterpower_托福阅读】xt>托福阅读tpo29(试题+答案+译文)第3篇:the history ofwaterpower_托福阅读重点单词查看全部解释obsolete [?bs?li:t] 想一想再看 adj. 已废弃的，过时的联想记忆 x 单词obsolete 联想记忆：ob不，solete用一不再用一过时的disagreement [.dis?gri:m?nt] 想一想再看 n. 不合，争论，不一致technical [teknik?l] 想一想再看 adj. 技术的，工艺的negative [neg?tiv] 想一想再看 adj. 否定的，负的，消极的n. 底片，负联想记忆 x 单词negative 联想记忆：negat否认+ive表形容词→否认的uncertainty [?ns?:tnti] 想一想再看 n. 不确定，不可靠，半信半疑(学术)不可信度; 偏差resolve [riz?lv] 想一想再看 n. 决定之事，决心，坚决vt. 决定，解决联想记忆 x 单词resolve 联想记忆：solve作为词根有溶解和解决两个意思。
托福阅读TPO29原文译文+答案
小编为托福考生们准备了托福阅读TPO29原文译文+答案,希望各位考生们在TPO真题里能够得到锻炼，祝广大托福考生能够取得理想成绩。
Characteristics of Roman PotteryThe pottery of ancient Romans is remarkablein several ways. The highquality of Roman potteryis very easy to appreciate when handling actualpieces oftableware or indeed kitchenware andamphorae (the large jars used throughout theMediterranean for the transport and storage ofliquids, such as wine and oil).However, it is impossible to do justice to Roman wares on thepage, even whenwords can be backed up by photographs and drawing. Most Roman pottery islightand smooth to touch and very tough, although, like all pottery, it shatters ifdropped ona hard surface. It is generally made with carefully selected andpurified clay, worked to thin-walled and standardized shapes on a fast wheel andfired in a kiln (pottery oven) capable ofensuring a consistent finish. Withhandmade pottery, inevitably there are slight differencesbetween individualvessels of the same design and occasional minor blemishes (flaws). Butwhatstrikes the eye and the touch most immediately and most powerfully with Romanpotteryis its consistent high quality.古罗马的陶器在诸多方面成就惊人。
托福TPO29综合写作文本+解析
小编为托福考生们准备了托福综合写作TPO29,希望各位考生们在TPO写作真题里能够得到锻炼，祝广大托福考生能够取得理想成绩。
综合写作 Reading Part:Large numbers of dinosaur fossils have been discovered in deposits onAlaska's North Slope, a region that today experiences an extremely cold, arcticclimate. One hundred million years ago, when those dinosaurs were alive, theenvironment of the North Slope was already inhospitable, especially during thewinter when it experienced several months of total darkness. How did thedinosaurs survive the wintertime? Paleontologists have proposed that one of themost common North Slope dinosaurs, the elephant-sized edmontosaur(Edmontosaurus), survived the winter by migrating south to more hospitableregions. Several arguments support the migration hypothesis.First, the edmontosaur's diet supports the migration hypothesis.Edmontosaurs fed exclusively on plants. Since there would have been no plantsgrowing during the cold and dark North Slope winter, it appears that theedmontosaur must have left for at least part of the year and migrated to moretemperate zones to find food.Second, many edmontosaur skeletons have been unearthed from the same site.This suggests that edmontosaurs lived in herd. Many modern-day migratoryanimals, such as caribou and buffalo, live and migrate in herds as well. Movingin herds helps animals coordinate their migration. The finding that edmonotsaurslived in herds further supports the migration hypothesis.Finally, edmonosaurs were physically capable of migrating long distances.To reach more hospitable regions, the edmontosaur had to migrate about 1,600kilometers southward. To make such a journey, the edmontosaur needed to move at about five kilometers per hour for several weeks, which is certainly could do. These animals could run very fast, reaching speeds up to 45 kilometers per hour. It could have easily used its locomotive power to move to warmer climate during the harsh arctic winters.综合写作 Listening Part:The hypothesis that the edmontosaur migrated every winter is notconvincing.First, the edmontosaur did not have to migrate to find food. One hundred million years ago the summer temperatures in the North Slope area were warmer than they are today. And remember in arctic regions like the North Slope the sun shines 24 hours a day at the peak of the summer, the warm temperatures and the extensive daylight created incredibly good growing conditions for plants, so much vegetation was produced during the summer that when the vegetation died as the winter came, there was a lot of nutritious dead vegetation around in the winter. The edmontosaur could have easily lived on the dead plant matter during in the winter.Second, just because edmontosaur lived in herds doesn’t mean they migrated. Animals lived in herds for many other reasons. Living in herds, for example, provides animals extra protection from predators. Having extra protection is useful even for the animals that live in the same area the whole year round. A modern example of this is the Roosevelt elk, a large plant-eater. Roosevelt elks live in the forests of western United States, they live in herds, but they do not migrate.。
托福阅读真题第29套
第29套Tree Species Identification in Tropical Rain ForestsIdentifying tree species in tropical rain forests may be harder than you think.Plant species identification can be difficult for all kinds of reasons even identification of trees,which are big and conspicuous.For example,for some willow trees,both leaves and flowers may be needed for identification,but the two may not be present at the same time.Yet whatever problems may confront us in temperate climates,we can be sure that the tropics will pose far worse difficulties.1.The word conspicuous in the passage is closest in meaning toA.close to each othermonC.easily noticedD.solitary2.ln paragraph1,why does the author discuss willow treesA.To provide an example of a tree that is unusually largeB.To explain the process of tree species identificationC.To support the idea that tropical trees can be more difficult to identify than temperate treesD.To demonstrate one reason why it can be problematic to determine what species a tree belongs toIn tropical rain forests，the flowers of a given tree species are typically not in bloom and so cannot be observed.In seasonal rain forests(with a distinct wet season and a distinct dry season),many trees adjust their flowering to the rains,so flowering is to some extent predictable.But much rain forest(as in much of the Amazon region)is nonseasonal,and trees may flower at any time.To be sure,different trees of the same species generally flower simultaneously,for if they did not,they could not pollinate each other.They must be responding to signals from the environment at large,or else (or in addition)they must be communicating with one another.But what those signals are is unknown,at least to us.To the human observer，the flowering seems random.In any case,in a tropical forest(at least in a secondary forest,which is forest that is regrowing after previous harvesting or clearance),the trees grow very close together，and most are remarkably thin，like poles，and grow straight up and disappear into the gloom,twenty meters overhead.Even if there are flowers，you would not necessarily see them.3.Paragraph2implies which of the following about tree flowering in seasonal rainforestsA.It is less predictable than tree flowering in tropical rain forestsB.It results from an unknown means of communication between the individual treesof each species.C.It is more useful to researchers trying to identify tree species than is the tree flowering in tropical rain forests.D.It follows the same pattern that tree flowering follows in a tropical secondary forest.4.In paragraph2，why does the author discuss pollinationA.To provide evidence that in many tropical tree species flowering is at least somewhat predictableB.To help explain why flowers on trees in tropical rainforests can be absent most of the timeC.To help explain why different trees of the same species bloom at the same timeD.To suggest one reason why trees might benefit from adjusting their flowering to the rains5.According to paragraph2，what is true about much of the Amazon regionA.It has tree species that adjust their pollination to rainfall.B.It has not yet been harvested or cleared.C.It has trees that typically flower during periods of rain.D.It does not have separate wet and dry seasons.The leaves may not be accommodating either,at least when viewed from the ground. Rain-forest trees all face the same kinds of conditions and have adapted in the same general kinds of way.Rain forests are wet by definition.But in some there is a dry season,and even when there is not,it doesn't rain all the time.Thus the forest floor may be moist，but the topmost leaves of the canopy are far above it and are exposed to the fiercest sun.So the uppermost leaves must resist desiccation(drying out).Yet from time to time,and in due season every day,they must also endure tremendous downpours.Leaves that can cope with such contrasts tend to be thick and leathery(to resist drought),oval in shape,and have a protection at the end known as a drip tip to let surplus rain run off the leaf.Many hundreds of trees from dozens of only distantly related families have leaves of this general type.But even if you can distinguish individual leaves,it is hard to be certain if they belong to the tree you are interested in or to the one next to it or to some epiphyte(a plant that grows on other plants)or liana (vine)slung over its branches.Often,in short,researchers must base their identification of a tree on the bark of its trunk.The trunks of tropical trees are sometimes highly characteristic,being deeply furrowed or twisted,but in most species the bark is simply smooth and gray，dappled with lichen and moss.6.The word endure in the passage is closest in meaning to withstandA.benefit fromB.avoidC.respond toD.withstand7.The word surplus in the passage is closest in meaning toA.heavyB.steadyC.suddenD.extra8.Paragraph3offers an explanation for each of the following characteristics of rain-forest tree leaves EXCEPTA.their having a drip-tip at the endB.their thicknessC.their leathery textureD.their oval shape9.According to paragraph3,what is one reason that looking at leaves may not be very useful when trying to determine the species of a rain-forest treeA.Leaves of rainforest trees often look very different when they are wet than when they are dry.B.Leaves that are exposed to the hot tropical sun dry out and lose their distinguishing characteristics.C.It can be hard to determine whether a leaf has a drip tip or not.D.It can be hard to determine whether a leaf belongs to a tree or to another plant growing on the tree.10.According to paragraph3,one reason that researchers in tropical forests must often rely on a tree’s bark for species identification is thatA.distinct species of tree often have similar kinds of lichens and moss growing on their trunksB.the leaves of many different tropical tree species are very similar to each other in appearanceC.many rainforest trees have neither epiphytes nor lianasD.the bark of the trees is less affected by changes in light and moisture than leaves are【In a temperate forest you can be fairly sure that any one tree is the same species as the one next to it or,at least，it will be one of a list that is unlikely to exceed more than half a dozen(oak with ash in much of Britain;lodgepole pine with aspen in the northernmost reaches of North America;alder,Scottish pine,and spruce in the Baltic; and so on).】But in the Amazon in particular，you can be fairly sure that any one tree is not the same species as the one next to it.Often there is a third of a mile between any two trees of the same species,and there can be up to120different species of trees in any one acre.So the task,often,is to identify an individual tree that may be not much thicker than your arm from the appearance of its bark,out of a total list of several hundred(or thousand)possibilities which may well include some that have notbeen described before,so that there is nothing to refer back to.11.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【In a temperate forest you can be fairly sure that any one tree is the same species as the one next to it or,at least，it will be one of a list that is unlikely to exceed more than half a dozen(oak with ash in much of Britain;lodgepole pine with aspen in the northernmost reaches of North America;alder,Scottish pine,and spruce in the Baltic; and so on).】A.Different temperate forests contain different combinations of tree species but in all such forests,all the trees of any one species are likely to be found close together.B.Temperate forests rarely contain more than about six species of tree,and trees growing next to each other tend to be of the same species.C.You can easily make a list of all the tree species that are likely to be found in temperate forests,and if one tree is not on that list，you can be confident that the tree next to it will be.D.Forests in Britain,in North America,and in the Baltic generally contain no more than half a dozen tree species,and all these species can be found on lists.12.The word task in the passage is closest in meaning toA.difficultyB.jobC.strategyD.requirement13.Look at the four squares that indicate where the following sentence could be added to the passage.As a result,the topmost level of a rainforest can be desert-like.Where would the sentence best fit.Click on a square to add the sentence to the passage.The leaves may not be accommodating either,at least when viewed from the ground. Rain-forest trees all face the same kinds of conditions and have adapted in the same general kinds of way.Rain forests are wet by definition.【A】But in some there is a dry season,and even when there is not,it doesn't rain all the time.【B】Thus the forest floor may be moist,but the topmost leaves of the canopy are far above it and are exposed to the fiercest sun.【C】So the uppermost leaves must resist desiccation (drying out).【D】Yet from time to time,and in due season every day,they must also endure tremendous downpours....14.Drag your choices to the spaces where they belong.To review the passage，click on View Text Answer ChoicesA.In tropical forests different trees of the same species flower at different times sothey are not able to pollinate one another.B.Flowering in tropical trees is often unpredictable and when it occurs,the flowers themselves tend to be too high up to be clearly visible.C.Many tropical tree species have leaves that look very similar from the ground,and because the trees often grow close together，correctly matching a leaf with a particular tree can be difficult.D.The leaves and bark of a single rain forest tree are often very different at different heights due to the need to adapt to different conditions,which adds to the difficulty of species identification.E.Because trees in rain forests are spaced closely together，it is easy to tell whether neighboring plants are the same species,but that is not much help in determining which species they are.F.Often,a rain-forest tree has to be identified by its bark,but trees of like species are widely scattered,the list of possible species is very long,and many have similar-looking bark.The Extinction of the DinosaursParagraph1:Geologists define the boundary between sediment layers of the Cretaceous period(144-65million years ago)and the Paleocene period(65-55million years ago)in part by the types and amounts of rocks and fossils they contain or lack. Before the limit of65million years ago，marine strata are rich in calcium carbonate due to accumulations of fossils of microscopic algae deposited on the sea floor.Above the65-million-year limit，sea-floor sediments contain much less calcium carbonate, and fossils of several families of mollusks are no longer found.In continental sediments,dinosaur fossils,though frequent before65million years ago,are totally absent.By contrast,new families of mammals appear,including large mammals for the first time.1..According to paragraph1，which of the following is true of Paleocene sediments ○They lack fossils from some families of mammals found in Cretaceous sediments.○They contain fossils of dinosaurs.○They contain fossils of some animals that did not exist during the Cretaceous.○They contain fossils of more kinds of mollusks than are found in Cretaceous sediments.Paragraph2:Scientists wondered for many years about what could have caused the dinosaurs'rapid disappearance at the end of the Cretaceous period,coming up with a great variety of theories and scenarios.For some,it could have been due to unfavorable genetic changes triggered by a dramatic increase by a factor of10，100，1，000in cosmic-ray particles reaching the Earth after a supernova explosion somewhere in the neighborhood of the solar system.For these high-energy particles to affect life，they would have to get through the protective barrier of the Earth's magnetosphere,the region of the upper atmosphere controlled by Earth's magneticfield.That could have happened if the cloud of particles from the supernova explosion reached the Earth during a period when the magnetosphere was weakened,something that may happen when the Earth's magnetic field changes direction.And we know that the magnetic north and south poles of the Earth switch on the average twice every million years.However,this is not the only possible explanation for dinosaur destruction.2..The word unfavorable in the passage is closest in meaning to○Unusual○Disadvantageous○Sudden○major3..The word triggered in the passage is closest in meaning to○Initiated○intensified○followed○aided4.Why does the author include the information that the magnetic north and south poles of the Earth switch on the average twice every million years○To provide evidence showing that Earth's protective barrier is difficult to get through○To show that it is reasonable to think that particles from a supernova explosion could have reached Earth○To explain why some scientists believe a supernova explosion may have occurred near our solar system○To help explain why some scientists have rejected the theory presented in Paragraph 25.According to the theory discussed in paragraph2，a weakening of Earth's magnetosphere may have○caused a supernova to explode near our solar system○allowed gene-altering particles to reach Earth's surface○forced Earth's magnetic field to change direction○allowed clouds of protective particles to escape from Earth's upper atmosphereParagraph3：Other theories have raised the possibility of strong climate changes in the tropics(but they then must be explained).Certainly，if climate changes，the changed distributions of temperature and rainfall modify the conditions that favor one ecosystem over another.The extinction of a particular family，genus，or species may result from a complicated chain of indirect causes and effects.Over thirty years ago, scientist Carl Sagan quoted one suggestion that the demise of the dinosaurs resulted from the disappearance of a species of fern plant that was important for dinosaurdigestion.Other theories involved a worldwide cold wave following the spread of a layer of cold but not very salty water in the world's oceans,which floated on the surface because，with its low salinity，the water was less dense.6..AII of the following are mentioned in paragraph3as possible causes for the extinction of the dinosaurs EXCEPT○a change in the diet of dinosaurs○a change in the climate of the tropics○a decrease in global temperatures○a decrease in deep ocean salinity7..ln paragraph3，why does the author include the quotation by Carl Sagan○To explain the connection between dinosaur extinction and the extinction of other animal species○To support the claim about species extinction being due to indirect causes and effects○To show that scientists have revised their ideas greatly in the last thirty years○To identify the differences between the various theories for the extinction of dinosaursParagraph4：Proponents of another theory that remains under consideration today postulate that the extinction of the dinosaurs corresponds to a period of intense volcanic activity.It's not a question of just one or even of a thousand eruptions comparable to the explosion of Krakatoa in1883，one of the largest volcanic events in modern times,but rather of a prolonged period of activity.On the Deccan plateau in India，basalt(volcanic)rocks cover more than500，000square kilometers(nearly200，000square miles)，and correspond to massive lava outflows occurring precisely at the end of the Cretaceous.This sort of outflow could correspond to volcanic activity similar to the activity that drives sea-floor spreading,with lava emerging from elongated fractures in the crust rather than from craters.8..According to paragraph4，what was one unusual aspect of the volcanic activity at the end of the Cretaceous○Some explosions were much larger than Krakatoa.○Eruptions occurred over a long period of time.○Active volcanoes were sometimes separated by many kilometers.○There were active volcanoes in the sea as well as on land.9..Which of the following is presented in paragraph4as evidence that intense volcanic activity occurred at about the time that the dinosaurs became extinct○The size of the volcanic craters on the Deccan plateau○An increase in sea-floor spreading○The formation in India of large amounts of a type of rock associated with volcanoes ○The occurrence of a thousand or more volcanic explosions the size of KrakatoaParagraph5：The volcanic convulsion that buried the Deccan plateau in lava must also have changed the composition of the atmosphere and severely affected climate. Initially，there must have been strong sudden cooling resulting from the blocking of sunlight by sulfate aerosol veils in the stratosphere(part of the Earth's atmosphere).If strong cooling lasted a year after the formation of the aerosols,it would have been the death of tropical species unable to adapt to such a volcanic winter.■However，a long period of strong volcanic activity(again，remember thousands of Krakatoas)would at the same time have added a substantial amount of carbon dioxide to the atmosphere, reinforcing the greenhouse effect.■This would gradually warm things up，ending the extended cold snap and producing global warming together with geographic shifts of humid and arid(dry)zones.■Certainly things would change to upset living conditions, leading to the extinction of some species while others would profit，if only from the disappearance of predators.■10.The word severely in the passage is closest in meaning to○certainly○consequently○greatly○Permanently11..The word reinforcing in the passage is closest in meaning to○making possible○spreading○introducing○strengthening12..According to paragraph5，all of the following are theorized to have occurred as a result of volcanic activity EXCEPT○a decrease in the amount of sunlight reaching Earth's surface○a reduction in the number of sulfate aerosol veils in the stratosphere○increased dryness in some areas that were once more humid○changes in the atmosphere's composition resulting in an increase in temperature13..Look at the four squares that indicate where the following sentence could be added to the passage.Thus,ecosystems following periods of extensive volcanic activity necessarily had different combinations of species than earlier ecosystems did.Where would the sentence best fit Click on a square to add the sentence to the passage.Paragraph5：The volcanic convulsion that buried the Deccan plateau in lava must also have changed the composition of the atmosphere and severely affected climate. Initially，there must have been strong sudden cooling resulting from the blocking ofsunlight by sulfate aerosol veils in the stratosphere(part of the Earth's atmosphere).If strong cooling lasted a year after the formation of the aerosols,it would have been the death of tropical species unable to adapt to such a volcanic winter.■However，a long period of strong volcanic activity(again，remember thousands of Krakatoas)would at the same time have added a substantial amount of carbon dioxide to the atmosphere, reinforcing the greenhouse effect.■This would gradually warm things up，ending the extended cold snap and producing global warming together with geographic shifts of humid and arid(dry)zones.■Certainly things would change to upset living conditions, leading to the extinction of some species while others would profit,if only from the disappearance of predators.■14..Drag your choices to the spaces where they belong.To review the passage，click on View TextAnswer Choices○Cosmic rays from a nearby supernova explosion may have penetrated Earth's atmosphere，causing genetic changes that dinosaur populations could not survive.○Climate changes in the tropics may have set off a chain of indirect effects that negatively affected the ecosystems in which dinosaurs lived.○The spread of lava over large parts of previously favored habitats such as the Deccan Plateau may have made these favored areas uninhabitable for many years.○Although the volcanic winter resulting from the formation of sulfate aerosols eventually ended，temperatures may have remained below levels required by dinosaurs to survive.○Temperature changes and geographic shifts in climate zones due to the atmospheric effects of volcanic activity may have been significant enough to cause extinction.○To be convincing,theories about what caused dinosaurs to become extinct must be able to explain the disappearance of other predators in the food chain at the same timeTree Species Identification in Tropical Rain ForestsTree Species Identification in Tropical Rain Forests答案：C D C C D;D D D D B;B B C CEFThe Extinction of the DinosaursThe Extinction of the Dinosaurs答案：C B A B B;D B B C C;D B D ABE。
tpo29阅读及答案解析
tpo29阅读及答案解析tpo29阅读试题1.The word "harnessed" in the passage(paragraph 1)is closest in meaning toA.known.B.depended on.C.recognized.D.utilized.2.In paragraph 1, uncertainty is expressed about all of the following aspects of the early development of waterpower EXCEPTA.when exactly the very first waterpower devices were invented.B.when exactly the very first waterpower devices were developed.C.whether water was one of the earliest sources of power to be used by humans.D.whether the very earliest waterpower devices arose independently.3.According to paragraph 2, what was true of the waterpower mills built throughout the Roman Empire?A.Most had horizontal-axis wheels.B.Their design was based on mills that had long been used in Scandinavia.C.Their design was more popular beyond the Empires boundaries than it was within the Empire.D.They are more advanced than the mills used in the Middle East at an earlier time.4.The phrase "the application of waterpower" in the passage (paragraph 3)is closest in meaning toA.the uses to which waterpower was put.B.the improvement made to waterpower.C.the method by which waterpower was supplied.D.the source of waterpower available.5.According to paragraph 4, which of the following was discovered as a result of scientific and technical investigations of waterpower conducted between 1650 and 1800?A.Some types of small waterwheel can produce as much horsepower as the very largest wheels.B.Waterwheels operate more efficiently when water falls away from their blades slowly than when water falls away quickly.C.Waterwheel efficiency can be improved by increasing the amount of kinetic energy water contains as it passes over a waterwheels blades.D.Unlike other types of waterwheels, the overshot wheel is capable of producing more than 60 horsepower units of energy.6.The word "pessimistic" in the passage is closest in meaning toA.negative.B.unlikely.C.surprising.D.incomplete.7.The term "by then" in the passage refers toA.by the time steam power entered the scene.B.by the year 1800.C.by the year 1900.D.by the time waterwheel was becoming obsolete.8.According to paragraph 5, why did waterpower become more importantly by 1900?A.Better waterwheel designs improved the efficiency of waterpower.B.Waterpower was needed to operate steam engines.C.Waterpower was used to generate electricity.D.Waterwheels became more efficient than coal-powered engines.9.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage paragraph 5? Incorrect choices change the meaning in important ways or leave out essential information.A.The growth of the electric-power industry stimulated significant changes in hydro technology and scientific progress in electrotechnology in the nineteenth century.B.The changes in hydro technology that led to the growth of the electric-power industry also led to discoveries and developments in electrotechnology in the nineteenth century.C.Advances in electrotechnology in the nineteenth century and changes in hydro technology were responsible for the growth of the electric-power industry.D.In the nineteenth century, the scientific study of electrotechnology and hydro technology。
托福阅读辅导：老托福阅读真题及答案passage29
托福阅读辅导:老托福阅读真题及答案passage29为了帮助大家备考托福阅读，练习更多阅读题目。
提高阅读水平，下面小编给大家带来托福阅读辅导:老托福阅读真题及答案PASSAGE 29，希望对大家有所帮助!:老托福阅读文本 passage29During the second half of the nineteenth century, the production of food and feed crops in the United States rose at an extraordinarily rapid rate. Corn production increased by four and a half times, hay by five times, oats and wheat by seven times. The most crucial factor behind this phenomenal upsurge in productivity was the widespread adoption of labor-saving machinery by northern farmers. By 1850 horse-drawn reaping machines that cut grain were being introduced into the major grain-growing regions of the country. Horse-powered threshing machines to separate the seeds from the plants were already in general use. However, it was the onset of the Civil War in 1861 that provided the great stimulus for the mechanization of northern agriculture. With much of the labor force inducted into the army and with grain prices on the rise, northern farmers rushed to avail themselves of the new labor-saving equipment. In 1860 there were approximately 80,000 reapers in the country; five years later there were 350,000.After the close of the war in 1865, machinery became ever more important in northern agriculture, and improved equipment was continually introduced. By 1880 a self-binding reaper had been perfected that not only cut the grain, but also gathered the stalks and bound them with twine. Threshing machines were also being improved and enlarged, and after 1870 they were increasingly powered by steam engines rather than byhorses. Since steam-powered threshing machines were costly items —running from $ 1,000 to $4,000 —they were usually owned by custom thresher owners who then worked their way from farm to farm during the harvest season. "Combines" were also coming into use on the great wheat ranches in California and the Pacific Northwest. These ponderous machines — sometimes pulled by as many as 40 horses — reaped the grain, threshed it, and bagged it, all in one simultaneous operation.The adoption of labor-saving machinery had a profound effect upon the sale of agricultural operations in the northern states — allowing farmers to increase vastly their crop acreage. By the end of century, a farmer employing the new machinery could plant and harvest two and half times as much corn as a farmer had using hand methods 50 years before.老托福阅读题目 passage291. What aspect of farming in the United States in the nineteenth century does the passage mainly discuss?(A) How labor-saving machinery increased crop Production(B) Why southern farms were not as successful as Successful as northern farms(C) Farming practices before the Civil War(D) The increase in the number of people farming2. The word "crucial" in line 4 is closest in meaning to(A) obvious(B) unbelievable(C) important(D) desirable3. The phrase "avail themselves" in line 11 is closest in meaning to(A) take care(B) make use(C) get rid(D) do more4. According to the passage , why was the Civil War a stimulus for mechanization?(A) The army needed more grain in order to feed the soldiers.(B) Technology developed for the war could also the used by farmers.(C) It was hoped that harvesting more grain would lower the price of grain.(D) Machines were needed to replace a disappearing labor force.5. The passage supports which of the following statements about machinery after the Civil War?(A) Many farmers preferred not to use the new machinery.(B) Returning laborers replaced the use of machinery.(C) The use of farm machinery continued to increase.(D) Poor-quality machinery slowed the pace of crop production.6. Combines and self-binding reapers were similar because each(A) could perform more than one function(B) required relatively little power to operate(C) was utilized mainly in California(D) required two people to operate7. The word "they" in line 19 refers to(A) grain stalks(B) threshing machines(C) steam engines(D) horses8. It can be inferred from the passage that most farmers did not own threshing machines because(A) farmers did not know how to use the new machines(B) farmers had no space to keep the machines(C) thresher owner had chance to buy the machines before farmers did(D) the machines were too expensive for every farmer to own9. The word "ponderous" in line 21 is closest in meaning to(A) advanced(B) heavy(C) complex(D) rapid老托福阅读答案 passage29ACBDC ABDB托福技巧：托福阅读做题要以TOEFL真题为基础托福阅读实战经验分享：词汇掌握了，你会发现阅读变得轻松很多。
托福TPO29综合写作阅读原文+听力原文+满分范文
¡¡¡¡ÎªÁË°ïÖú´ó¼Ò¸ßЧ±¸¿¼Íи££¬Îª´ó¼Ò´øÀ´Íи£TPO29×ÛºÏд×÷ÔĶÁÔ-ÎÄ+ÌýÁ¦Ô-ÎÄ+Âú·Ö·¶ÎÄ£¬Ï£Íû¶Ô´ó¼Ò±¸¿¼ÓÐËù°ïÖú¡£¡¡¡¡Íи£TPO29×ÛºÏд×÷ÔĶÁÔ-ÎÄÎı¾£º¡¡¡¡Large numbers of dinosaur fossils have been discovered in deposits on Alaska's North Slope, a region that today experiences an extremely cold,arctic climate. One hundred million years ago, when those dinosaurs were alive, the environment of the North Slope was already inhospitable,especially during the winter when it experienced several months of total darkness. How did the dinosaurs survive the wintertime? Paleontologists have proposed that one of the most common North Slope dinosaurs, the elephant-sized edmontosaur (Edmontosaurus), survived the winter by migrating south to more hospitable regions. Several arguments support the migration hypothesis. First, the edmontosaur's diet supports the migration hypothesis.Edmontosaurs fed exclusively on plants. Since there would have been no plants growing during the cold and dark North Slope winter, it appears that the edmontosaur must have left for at least part of the year and migrated to more temperate zones to find food. Second, many edmontosaur skeletons have been unearthed from the same site. This suggests that edmontosaurs lived in herd. Many modern-day migratory animals, such as caribou and buffalo, live and migrate in herds as well. Moving in herds helps animals coordinate their migration.The finding that edmonotsaurs lived in herds further supports the migration hypothesis. Finally, edmonosaurs were physically capable of migrating long distances. To reach more hospitable regions, the edmontosaur had to migrate about 1,600 kilometers southward. To make such a journey, the edmontosaur needed to move at about five kilometers per hour for several weeks, which is certainly could do. These animals could run very fast, reaching speeds up to 45 kilometers per hour. It could have easily used its locomotive power to move to warmer climate during the harsh arctic winters.¡¡¡¡Íи£TPO29×ÛºÏд×÷ÌýÁ¦Ô-ÎÄÎı¾£º¡¡¡¡ProfessorThe hypothesis that the Edmontosaur migrated every winter is not convincing.First, the Edmontosaur did not have to migrate to find food. Once hundred million years ago, the summer temperatures in the North Slope area were warmer than they are today. And remember, in arctic regions like the North Slope, the Sun shines 24 hours a day at the peak of the summer. The warm temperatures and extensive daylight created incredibly good growing conditions for plants, so much vegetation was produced during the summer that when the vegetation died as the winter came, there was a lot of nutritious dead vegetation around in the winter. The Edmontosaur could have easily lived on the dead plant matter during the winter.Second, just because Edmontosaurs lived in herds doesn't mean they migrated. Animals live in herds for many other reasons. Living in herds, for example, provides animals with extra protection from predators. Having extra protection is useful even for the animals that live in the same area the whole year around. A modern example of this is the Roosevelt elk¡ªa large plant-eater. Roosevelt elks live in the forests of the western United States. They live in herds but they do not migrate.Third, although adult Edmontosaurs were capable of migrating long distances, what about Edmontosaurs that were not yet adults? Juvenile Edmontosaurs were not physically capable of travelling the great distances required to reach warmer territories and would have slowed the herd so much that the herd never would have made it to its destination. The herd could not have left the juveniles behind because the juveniles would not have survived on their own. So the whole herd had to stay where they were and survive on the cold North Slope.¡¡¡¡Íи£TPO29×ÛºÏд×÷Âú·Ö·¶ÎÄ1£º¡¡¡¡In the reading passage, the writer claim that edmontosaurus had to migrate to hospitable places in the south, if they want to survive in the cold weather. The speaker, however, contradicts this view for the following three reasons. First of all, the reading materials points out that it is difficult that edmontosaurus to find food in cold winter because of they were fed on plants exclusively. But the speaker reputes that warm weather in summer supplied perfect condition for plants to grow. So edmontosaurus might found lots of nutritious dead vegetation around in the winter, which made migration unnecessary. Second, unearthed skeletons from the same site indicated that edmontosaurus lived in herds. Living in herds made migration much easy. But the lecture gave an example of Roosevelt elks to prove that group living might have various types of reasons. So edmontosaurus may live in herds in order to seek for extra protection. So living in herds could not provide evidence for migration claim. Lastly, edmontosaurus, in view of the writer, had the ability of long-distance movement. Although the lecturer admitted the locomotive capability of edmontosaurus, he points out that juvenile edmontosaurus were lack of such ability. So the herd would not leave juveniles behind in the North Slope, which strongly reputes the author¡¯s claim.¡¡¡¡Íи£TPO29×ÛºÏд×÷Âú·Ö·¶ÎÄ2£º¡¡¡¡In the reading passage, the writer proposes several arguments to support the hypothesis that in order to survive the winter, edmontosaur would migrate south to more hospitable regions. The speaker, however, contradicts this view for the following three reasons. First of all, the reading materials points out that since edmontosaurus fed exclusively on plants, it was difficult for edmontosaurus to find food in cold winter because no plants growing during the cold and dark North Slope winter. But the speaker reputes that the temperature in North Sloper were much warmer than they are today. So warm weather in summer supplied perfect condition for plants to grow, and edmontosaurus might found lots of nutritious dead vegetation around in the winter, which made migration unnecessary. Second, unearthed skeletons from the same site indicated that edmontosaurus lived in herds. Living in herds made migration much easier, which is a strong support for migration. But the lecture gives an example of Roosevelt elks to show that animals live in groups for various reasons,。
TPO-29 Reading 2解析
Q1正确答案：D解析：mechanism本身是机制，原理的意思。
与“自然选择原理”意思最接近的是D项，从原文也可以推断出来，进化是“物竞天择”的结果。
Q2正确答案：D解析：题干内容competition among individuals of different species出现在该段第4句，种族间竞争的effect需要定位到第5句，主语是代词it，指代了interspecies competition，句意是物种间竞争是controlling the size of competition populations和导致种族灭绝的因素，对应D项。
Q3正确答案：A解析：indigenous，本土的，固有的，土著的，原产的；近义词是native，本地的，土著的。
rare，稀少的；numerous，无数的。
该段最后半句，which引导的从句说由于欧洲引进的物种和新西兰的物种竞争，导致新西兰物种灭绝，是对上一句it(competition) may lead to the extinction of one species的例证，外来物种与本土物种竞争导致本土物种灭绝。
Q4正确答案：B解析：这一段第5句提到物种间竞争可以控制不同物种的数量，并可能导致物种灭绝。
然后第6句举用新西兰动植物的灭绝作为例子（外来物种与本土物种竞争导致本土物种灭绝），例证“竞争可能导致物种灭绝”。
Q5正确答案：D解析：定位到该段第1句“No serious competition exists when the major needed resources is in superabundant supply, as in most cases of the coexistence of herbivores (plant eaters)” 说明了竞争不是影响食草动物间共生的主要因素。
Q6正确答案：A解析：graph是图画的意思，可推知graphically是“图形地，生动地”之意。
托福备考托福阅读34套TPO样题+解析+译文29—2 Competition
托福考试 复习TPO 29—2 Competition原文：【1】When several individuals of the same species or of several different species depend on the same limited resource, a situation may arise that is referred to as competition. The existence of competition has been long known to naturalists; its effects were described by Darwin in considerable detail. Competition among individuals of the same species (intraspecies competition), one of the major mechanisms of natural selection, is the concern of evolutionary biology. Competition among the individuals of different species (interspecies competition) is a major concern of ecology. It is one of the factors controlling the size of competing populations, and extreme cases it may lead to the extinction of one of the competing species. This was described by Darwin for indigenous New Zealand species of animals and plants, which died out when competing species from Europe were introduced.【2】No serious competition exists when the major needed resource is in superabundant supply, as in most cases of the coexistence of herbivores (plant eaters). Furthermore, most species do not depend entirely on a single resource, if the major resource for a species becomes scarce, the species can usually shift to alternative resources. If more than one species is competing for a scarce resource, the competing species usually switch to different alternative resources. Competition is usually most severe among close relatives with similar demands on the environment. But it may also occur among totally unrelated forms that compete forthe same resource, such as seed-eating rodents and ants. The effects of such competition are graphically demonstrated when all the animals or all the plants in an ecosystem come into competition, as happened 2 million years ago at the end of Pliocene, when North and South America became joined by the Isthmus of Panama. North and South American species migrating across the Isthmus now came into competition with each other. The result was the extermination of a large fraction of the South American mammals, which were apparently unable to withstand the competition from invading North American species—although added predation was also an important factor.【3】To what extent competition determines the composition of a community and the density of particular species has been the source of considerable controversy. The problem is that competition ordinarily cannot be observed directly but must be inferred from the spread or increase of one species and the concurrent reduction or disappearance of another species. The Russian biologist G. F. Gause performed numerous two-species experiments in the laboratory, in which one of the species became extinct when only a single kind of resource was available. On the basis of these experiments and of field observations, the so-called law of competitive exclusion was formulated, according to which no two species can occupy the same niche. Numerous seeming exceptions to this law have since been found, but they can usually be explained as cases in which the two species, even though competing for a major joint resource, did not really occupy exactly the same niche.【4】Competition among species is of considerable evolutionary importance. Thephysical structure of species competing for resources in the same ecological niche tends to gradually evolve in ways that allow them to occupy different niches. Competing species also tend to change their ranges so that their territories no longer overlap. The evolutionary effect of competition on species has been referred to as “species selection”; however, this description is potentially misleading. Only the individuals of a species are subject to the pressures of natural selection. The effect on the well-being and existence of a species is just the result of the effects of selection on all the individuals of the species. Thus species selection is actually a result of individual selection.【5】Competition may occur for any needed resource. In the case of animals it is usually food; in the case of forest plants it may be light; in the case of substrate inhabitants it may be space, as in many shallow-water bottom-dwelling marine organisms. Indeed, it may be for any of the factors, physical as well as biotic, that are essential for organisms. Competition is usually the more severe the denser the population. Together with predation, it is the most important density-dependent factor in regulating population growth.题目：1.The phrase "mechanisms of natural selection" in the passage（paragraph 1）is closest in meaning toA.types of natural selection.B.dangers of natural selection.C.problems natural selection solves.D.ways natural selection works.2.According to paragraph 1, what is one effect of competition among individuals of different species?A.It results in the eventual elimination of the resource for which they are competing.B.It leads to competition among individuals of the same species.C.It encourages new species to immigrate to an area.D.It controls the number of individuals in the competing populations.3.The word "indigenous" in the passage（paragraph 1）is closest in meaning toA.native.B.rate.C.most.D.numerous.4.In paragraph 1, why does the author mention what happened in New Zealand?A.T o indicate that Darwin understood the importance of competition.B.To illustrate that competition can lead to the extinction of species.C.To identify where the idea of competition among species first arose.D.T o argue against the idea that the process of selection is a natural occurrence.5.According to paragraph 2, competition is not usually a significant factor among two coexisting species whenA.one of the species has only recently moved into the territory of the other.B.the species are closely related to each other.C.the population of one species is much larger than that of the other.D.both of the species are herbivores.6.The word "graphically" in the passage（paragraph 2）is closest in meaning toA.vividly.B.frequently.C.broadly.D.typically.7.In paragraph 2, why does the author talk about what happened as a result of North and South America becoming joined at the Isthmus of Panama?A.T o make the point that predation can have as much effect on species survival as competition does.B.To show how the ability to switch to an alternative resource can give a species a competitive advantage.C.To account for the current species composition of North and South America.D.T o provide an example of the serious effects of competition between unrelated species.8.Paragraph 3 supports the idea that Gause's experiments were important because theyA.provided a situation in which competition could be removed from the interaction between two species.B.showed that previous ideas about the extent to which competition determines thecomposition of a community were completely mistaken.C.helped establish that competition will remove all but one species from any given ecological niche.D.offered evidence that competition between species is minimal when there is an overabundance of a single food source.9.Which of the sentences below best expresses the essential information inthe highlighted sentence in the passage（paragraph 3）? Incorrect choices change the meaningin important ways or leave out essential information.A.Apparent exceptions to this law usually involves cases in which two species compete for the same major resource but occupy slightly different niches.B.Although it may appear that two species always have different niches, many exceptions show that species compete with each other.C.Cases in which two species not only compete for a shared resource but also occupy similar niches are considered exceptions to this law.D.Cases in which the two species do not occupy that same niche yet still compete for the same resource are believed to be exceptions to this law.10.According to paragraph 4, how does competition affect evolution?A.It results in the evolution of physical structures that allow the species to compete with each other more effectively.B.It results I the evolutionary extinction of all but one of the competing species.C.It results in the competing species evolving in such a way that they no longer compete for the same resources.D.It results in the competing species evolving to become so much like each other that competition between them eventually disappears.11.According to paragraph 4, "species selection" is a misleading term because itA.overemphasizes the role of selection pressure in species extinction.B.suggests that selection pressures directly influence whole species.C.does not make a distinction between species extinction and species evolution.D.suggests that extinction always results whenever there is a competition.12.The word "regulating" in the passage（paragraph 5）is closest in meaning toA.controlling.B.explaining.C.observing.D.stopping.13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.Where would the sentence best fit? That is, as the density of a population increases, competition has a greater impact and leads to greater mortality.Competition may occur for any needed resource. ■【A】In the case of animals it is usually food; in the case of forest plants it may be light; in the case of substrate inhabitants it may be space, as in many shallow-waterbottom-dwelling marine organisms. ■【B】Indeed, it may be for any of the factors,physical as well as biotic, that are essential for organisms. ■【C】Competition isusually the more severe the denser the population. ■【D】Together with predation, itis the most importantdensity-dependent factor in regulating population growth.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. This question is worth 2 points.When necessary resources are limited, competition can occur among individuals of the same species or of different species.petition can eliminate a species, but since most species do not depend on a single resource, competition is often reduced by switching to alternative resources.B.Investigation of the ecological role of competition is difficult because ordinarily the competition cannot be observed directly and must be inferred from its presumed effects.petition between a pair of species tends to lessen over time because the species tend to evolve to occupy different ecological niches and ranges.petition between individual of the same species is usually for food whereas competition between species is usually for habitat.E.Experiments and field observation have established that competition between species is strong enough to prevent two species from occupying the same ecological niche.petition is usually strongest when the density of the competing populations is the same.答案：1.Mechanism本身是机制，原理的意思。
托福作文TPO29英文范文及解析
TPO 29The world over, education is the epitome of a prosperous country. However, the system and ways of educating are becoming complicated as many people try to forge out what would be the meritorious way of remedying the quality of education at universities. It is a common outcry that professors' salaries being augmented is one of the cardinal solutions to improving the quality of education. These are custodians of knowledge to whom students look up to for better performance so as to have a good career in life. I do partake that it actually holds water to increase professors’ salaries.It is prudent to say that professors being the main tap of knowledge for students need to have a contented heart to impart knowledge, and one of the ways of being gratified is to hike their pay. In fact, a horde of professors that are paid less do not have the urge of teaching students as teaching itself is meant to be, but teach because it is the only likelihood of earning something. In many countries, professors eat by the hand, and are evoked into doing jobs outside their normal teaching schedule. In this way, there is little preparationfor lectures and at the end, performances are in a worrying state. To come to terms with the increasing standard of living so as to avoid such behavior, professors should earn a substantial fee.Suffice to say, the world is changing at a supersonic speed and the professors are not an exception in that they need to move with the blowing trend by taking upgrading courses so as to meet the requirements of the education system. For example, the education system is becoming advanced with different technologies. Numerous disciplines at university need upgrading in the way of teaching, not to mention the content to teach. Traditional ways of teaching are wading and becoming a myth. The only way for professors to acquire updated information is to have a higher pay that can enable them to be at par with the changing education trends. Only through an increased pay can professors make good research towards elevating their knowledge and adjusting to the new trends of education.Today, many a person is shunning away from the education field because many careers now do offer a hefty package. This has bred ashortage of virtuous professors in many countries as the few that join do join as a last resort to enable them warm their pockets. Many university students take on other majors like accountancy and technological fields than education because they are more enticing than lecturing. Lecturing is becoming a career for students that are deemed failures in other fields. To revive the career, and to have more qualified professors to attain quality education, professors ought to pocket a reasonable amount of money so as to entice the gem among students to join the profession.By and large, though I do believe that other solutions do carry water, like enhancing school facilities and awarding scholarships, it is common sense to know that all these will also rotate around a professor as students can hardly accomplish tasks in different fields without the help of professors. With no doubt, increasing professors' pay is the primal solution to consummating noble education, for it molds them into contentment so as to prepare well for their lectures, it entices refulgent students and above all, accords them the possibility of improving themselves academically.满分要素剖析：一、语言表达本文多用长句，句子当中使用了不少插入语，因此句子虽然篇幅较长但是逻辑比较清晰。
tpo29阅读答案解析
tpo29阅读答案解析tpo29阅读答案解析：Characteristics of Roman PotteryQ1正确答案：B对应原文第二句。
A原文并没有对amphorae和pottery的比较。
C原文提到了快速转轮和烧窑的使用，但并没说因此陶器质量就下降了。
D提到了陶器在Mediterranean的广泛使用，但是没有种类间的比较。
Q2正确答案：C对应红色标记部分。
只有C和原文的描写冲突。
Q3正确答案：D四个选项分别对应红色标记部分。
D选项对应的最后一句和原文矛盾，原文说一眼看上去这个pot是非常现代化的。
但实际很古老了。
因此its true age 并不明显。
D错误。
Q4正确答案：A这一段的主题就是第一句，强调了massive quantity。
因此后面提到work of archaelogists也是为了支持这个主题。
因此选A。
Q5正确答案：CSubstantial是大量的，实质的等意。
A是保护的;B是人工的;D是著名的。
只有C是大的。
所以选择C。
而且这里也描述了50 meters high也是描述了它的大小。
所以应选择与大小有关的。
Q6正确答案：C这里介绍Monte Testaccil是在支持本段的论点。
回到原文这段的第一句可以看到原文说“很难通过broken pot来确定那个时期的pot产量，而Monte Testaccil确实个例外。
所以也就是说可以通过这个dump遗址得到当时的quantities。
选CQ7正确答案：BEntirely是完全的，整个的。
A是明显的，B是完全的，C是基本的，D是大部分的。
这里B最符合。
Q8正确答案：D根据tiber river定位，看到后面的描述说around 6000 million liters of oil were imported into city form oversea。
那么也就是说当时的进出口贸易非常繁华。
对应答案DQ9 .正确答案：C根据原文discarded定位到原文最后一句。
托福备考托福阅读34套TPO样题+解析+译文29—1 Characteristics of Roman Pottery
托福考试 复习TPO 29—1 Characteristics of Roman Pottery原文：【1】The pottery of ancient Romans is remarkable in several ways. The high quality of Roman pottery is very easy to appreciate when handling actual pieces of tableware or indeed kitchenware and amphorae (the large jars used throughout the Mediterranean for the transport and storage of liquids, such as wine and oil). However, it is impossible to do justice to Roman wares on the page, even when words can be backed up by photographs and drawing. Most Roman pottery is light and smooth to touch and very tough, although, like all pottery, it shatters if dropped on a hard surface. It is generally made with carefully selected and purified clay, worked to thin-walled and standardized shapes on a fast wheel and fired in a kiln (pottery oven) capable of ensuring a consistent finish. With handmade pottery, inevitably there are slight differences between individual vessels of the same design and occasional minor blemishes (flaws). But what strikes the eye and the touch most immediately and most powerfully with Roman pottery is its consistent high quality. 【2】This is not just an aesthetic consideration but also a practical one. These vessels are solid (brittle, but not fragile), they are pleasant and easy to handle (being light and smooth), and, with their hard and sometimes glossy (smooth and shiny) surfaces, they hold liquids well and are easy to wash. Furthermore, their regular and standardized shapes would have made them simple to stack and store. When people today are shown a very ordinary Roman pot and, in particular, are allowed to handle it, they often comment on how modern it looks and feels, and they needto be convinced of its true age.【3】As impressive as the quality of Roman pottery is its sheer massive quantity. When considering quantities, we would ideally like to have some estimates for overall production from particular sites of pottery manufacture and for overall consumption at specific settlements. Unfortunately, it is in the nature of the archaeological evidence, which is almost invariable only a sample of what once existed, that such figures will always be elusive. However, no one who has ever worked in the field would question the abundance of Roman pottery, particularly in the Mediterranean region. This abundance is notable in Roman settlements (especially urban sites) where the labor that archaeologists have to put into the washing and sorting of potsherds (fragments of pottery) constitutes a high proportion of the total work during the initial phases of excavation.【4】Only rarely can we derive any “real”quantities from deposits of broken pots. However, there is one exceptional dump, which does represent a very large part of the site’s total history of consumption and for which an estimate of quantity has been produced. On the left bank of the Tiber River in Rome, by one of the river ports of the ancient city, is a substantial hill some 50 meters high called Monte Testaccio. It is made up entirely of broken oil amphorae, mainly of the second and third centuries A.D. It has been estimated that Monte Testaccio contains the remains of some 53 million amphorae, in which around 6,000million liters of oil were imported into the city from overseas, imports into imperial Rome were supported by the full might of the state and were therefore quite exceptional—but the size of theoperations at Monte Testaccio, and the productivity and complexity that lay behind them, nonetheless cannot fail to impress. This was a society with similarities to modern one—moving goods on a gigantic scale, manufacturing high-quality containers to do so, and occasionally, as here, even discarding them on delivery. 【5】Roman pottery was transported not only in large quantities but also over substantial distances. Many Roman pots, in particular amphorae and the fine wares designed for use at tables, could travel hundreds of miles—all over the Mediterranean and also further afield. But maps that show the various spots where Roman pottery of a particular type has been found tell only part of the story. What is more significant than any geographical spread is the access that different levels of society had to good-quality products. In all but the remotest regions of the empire, Roman pottery of a high standard is common at the sites of humble villages and isolated farmsteads题目：1.Paragraph 1 indicates which of the following about Roman pottery?A.Roman amphorae were of much higher quality overall than other Roman pottery.B.Roman pottery can best be appreciated when actual pieces are handled.C.Roman pottery declined slightly in quality when the use of fast wheels and kilns was introduced.D.Roman practical tableware spread more rapidly across the Mediterranean than amphorae did.2.All of the following are mentioned in paragraph 1 as characteristics of Roman pottery EXCEPTA.It was usually made with high-quality clay.B.It generally did not weigh much.C.It did not break as easily as other ancient pottery.D.It sometimes had imperfections.3.According to paragraph 2, which of the following is NOT true of Roman vessels?A.They were good containers for liquids.B.Their shapes allowed for easy stacking and storing.C.They sometimes had shiny surfaces.D.Their true age is immediately apparent.4.The author mentions the work of archaeologists in paragraph 3 in order toA.support the idea that pottery was produced in large quantities by the Romans.B.illustrate how hard it is for archaeologists to find complete pieces of Roman pottery.C.contrast archaeological sites in Roman urban areas with other sites in the Mediterranean.D.explain why the quantities of pottery found vary significantly from one site to another.5.The word "substantial" in the passage（paragraph 4）is closest in meaning toA.protected.B.man-made.rge.D.famous.6.According to paragraph 4, Monte Testaccio is particularly important forarchaeologists because archaeologists were able toA.conclude how amphorae manufacturing increased rapidly after the second century A.D..B.find the locations where most of the amphorae in the Roman Empire were produced.C.obtain relatively accurate calculations of the quantities of amphorae used over time in that place.D.discover that the Roman state had supported amphorae production.7.The word "entirely" in the passage（paragraph 4）is closest in meaning toA.apparently.pletely.C.basically.D.mostly.8.Paragraph 4 indicates which of the following about the port on the Tiber River near Monte Testaccio?A.It was built around the third century A.D..B.It was close to areas where large quantities of oil were produced.C.It was in use only for a very short period of time.D.It had impressive level of commercial activity.9.The statement in paragraph 4 that amphorae delivered to the port near Monte Testaccio were occasionally discarded support which of the following?A.Traders at the port were often careless.B.The quality of the amphorae used at the port was not very good.C.The scale of the trade made it possible to waste quality amphorae sometimes.D.The importing of oil from overseas gradually declined, reducing the need for pottery containers.10.The statement that "maps show the various spots where Roman pottery of aparticular type has been found tell only part of the story" makes the point that A.maps indicate where specific pottery styles have been found, but they do not indicate where these styles originated.B.maps show the geographical spread of Roman pottery but not the people who had access to it.C.maps do not usually include pottery styles found in the remotest regions the Roman Empire.D.archaeologist studying Roman pottery need to use a range of techniques in their investigations.11.The word "humble" in the passage is closest in meaning toA.rural.B.distant.C.ancient.D.modest.12.The word "particular" in the passage is closest in meaning toA.specific.mon.C.ancient.D.superior.13. Look at the four squares [■] that indicate where the following sentence could be added to the passage. Where would the sentence best fit? That is because residents of a city did not usually discard used pottery at the same site over a long period of time.■【A】Only rarely can we derive any "real" quantities from deposits of brokenpots. ■【B】However, there is one exceptional dump, which does represent a very large part of the site's total history of consumption and for which an estimate of quantity has been produced. ■【C】On the left bank of the Tiber River in Rome, by one of the river ports of the ancient city, is a substantial hill some 50 meters high called Monte Testaccio. ■【D】It is made up entirely of broken oil amphorae, mainly of the second and third centuries A.D. It has been estimated that Monte Testaccio contains the remains of some 53 million amphorae, in which around 6,000 million liters of oil were imported into the city from overseas,imports into imperial Rome were supported by the full might of the state and were therefore quite exceptional- but the size of the operations at Monte Testaccio, and the productivity and complexity that lay behind them,nonetheless cannot fail to impress. This was a society with similarities to modernone-moving goods on a gigantic scal, manufacturing high-quality containers to do so, and occasionally, as here, even discarding them on delivery.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. This question is worth 2 points.The pottery of the ancient RomanEmpire is remarkable.A.Roman pottery is considered to be practical and of consistently high quality.B.Roman pottery was transported over long distances, and different levels of society had access to quality pottery.C.Archaeologists looking for the remains of Roman pottery concentrate on urban sites because that is where the oldest pieces of kitchenware and amphorae have been found.D.Even though the exact quantity of pottery produced by the Romans is almost impossible to calculate, it is certain that is was produced in large quantities.E.People are not familiar with the whole range of pottery of Romans created because most of the available pieces represent only a limited number of styles and shapes.F.It is still unclear to archaeologists what the role of the Roman state in the commercial success of Roman pottery was.答案：1.对应原文第二句。
tpo29阅读及答案
tpo29阅读及答案tpo29阅读原文【1】The pottery of ancient Romans is remarkable in several ways. The high quality of Romanpottery is very easy to appreciate when handling actual pieces of tableware or indeedkitchenware and amphorae (the large jars used throughout the Mediterranean for thetransport and storage of liquids, such as wine and oil). However, it is impossible to do justiceto Roman wares on the page, even when words can be backed up by photographs and drawing.Most Roman pottery is light and smooth to touch and very tough, although, like all pottery, itshatters if dropped on a hard surface. It is generally made with carefully selected and purifiedclay, worked to thin-walled and standardized shapes on a fast wheel and fired in a kiln(pottery oven) capable of ensuring a consistent finish. With handmade pottery, inevitablythere are slight differences between individual vessels of the same design and occasional minorblemishes (flaws). But what strikes the eye and the touch most immediately and mostpowerfully with Roman pottery is its consistent high quality.【2】This is not just an aesthetic consideration but also a practical one. These vessels aresolid (brittle, but not fragile), they are pleasant and easy to handle (being light and smooth),and, with their hard and sometimes glossy (smooth and shiny) surfaces, they hold liquids welland are easy to wash. Furthermore, their regular and standardized shapes would have madethem simple to stack and store. When people today are shown a very ordinary Roman pot and,in particular, are allowed to handle it, they often comment on how modern it looks and feels,and they need to be convinced of its true age.【3】As impressive as the quality of Roman pottery is its sheer massive quantity. Whenconsidering quantities, we would ideally like to have some estimates for overall production fromparticular sites of pottery manufacture and for overall consumption at specific settlements.Unfortunately, it is in the nature of the archaeological evidence, which is almost invariableonly a sample of what once existed, that such figures will always be elusive. However, no onewho has ever worked in the field would question the abundance of Roman pottery, particularlyin the Mediterranean region. This abundance is notable in Roman settlements (especiallyurban sites) where the labor that archaeologists have to put into the washing and sorting ofpotsherds (fragments of pottery) constitutes a high proportion of the total work during theinitial phases of excavation.【4】Only rarely can we derive any “real” quantities from deposits of broken pots. However,there is one exceptional dump, which does represent a very large part of the sites totalhistory of consumption and for which an estimate of quantity has been produced. On the leftbank of the Tiber River in Rome, by one of the river ports of the ancient city, is a substantialhill some 50 meters high called Monte Testaccio. It is made up entirely of broken oil amphorae,mainly of the second and third centuries A.D. It has been estimated that Monte Testacciocontains the remains of some 53 million amphorae, in which around 6,000million liters of oil wereimported into the city from overseas, imports into imperial Rome were supported by the fullmight of the state and were therefore quite exceptional—but the size of the operations atMonte Testaccio, and the productivity and complexity that lay behind them, nonethelesscannot fail to impress. This was a society with similarities to modern one—moving goods on agigantic scale, manufacturing high-quality containers to do so, and occasionally, as here,even discarding them on delivery.【5】Roman pottery was transported not only in large quantities but also over substantialdistances. Many Roman pots, in particular amphorae and the fine wares designed for use attables, could travel hundreds of miles—all over the Mediterranean and also further afield. Butmaps that show the various spots where Roman pottery of a particular type has been foundtell only part of the story. Whatis more significant than any geographical spread is the accessthat different levels of society had to good-quality products. In all but the remotest regions ofthe empire, Roman pottery of a high standard is common at the sites of humble villages andisolated farmsteadstpo29阅读题1.Paragraph 1 indicates which of the following about Roman pottery?A.Roman amphorae were of much higher quality overall than other Roman pottery.B.Roman pottery can best be appreciated when actual pieces are handled.C.Roman pottery declined slightly in quality when the use of fast wheels and kilns wasintroduced.D.Roman practical tableware spread more rapidly across the Mediterranean than amphorae did.2.All of the following are mentioned in paragraph 1 as characteristics of Roman potteryEXCEPTA.It was usually made with high-quality clay.B.It generally did not weigh much.C.It did not break as easily as other ancient pottery.D.It sometimes had imperfections.3.According to paragraph 2, which of the following is NOT true of Roman vessels?A.They were good containers for liquids.B.Their shapes allowed for easy stacking and storing.C.They sometimes had shiny surfaces.D.Their true age is immediately apparent.4.The author mentions the work of archaeologists in paragraph 3 in order toA.support the idea that pottery was produced in large quantities by the Romans.B.illustrate how hard it is for archaeologists to find complete pieces of Roman pottery.C.contrast archaeological sites in Roman urban areas with other sites in the Mediterranean.D.explain why the quantities of pottery found vary significantly from one site to another.5.The word "substantial" in the passage(paragraph 4)is closest in meaning toA.protected.B.man-made.rge.D.famous.6.According to paragraph 4, Monte Testaccio is particularly important forarchaeologistsbecause archaeologists were able toA.conclude how amphorae manufacturing increased rapidly after the second century A.D..B.find the locations where most of the amphorae in the Roman Empire were produced.C.obtain relatively accurate calculations of the quantities of amphorae used over time in thatplace.D.discover that the Roman state had supported amphorae production.7.The word "entirely" in the passage(paragraph 4)is closest in meaning toA.apparently.pletely.C.basically.D.mostly.8.Paragraph 4 indicates which of the following about the port on the Tiber River nearMonte Testaccio?A.It was built around the third century A.D..B.It was close to areas where large quantities of oil were produced.C.It was in use only for a very short period of time.D.It had impressive level of commercial activity.9.The statement in paragraph 4 that amphorae delivered to the port near MonteTestaccio were occasionally discarded support which of the following?A.Traders at the port were often careless.。
托福考试阅读题目详细解析(29)
托福考试阅读题目详细解析(29)2017年7月8日题目：European Green Crab: Tough Survivor大致内容GreenCrab，原产地在欧洲西海岸，但通过shiptransportation的方式逐渐widesprea d the world。
它能够生存是因为对环境有适应力，适应温度能力较强，食物来源广泛，繁殖能力很强，并且因为体型较小，人类不会进行捕杀。
相对Asian crab and blue crab有较强竞争力。
因为more robustbody。
科学家通过实验发现green crab找到食物location 的能力更强，并且有更强的食物争夺能力，虽然Asian crab is more aggressive文章“欧洲绿色螃蟹：强悍的生存者”，主要介绍欧洲的绿色螃蟹为什么能够随人类到达北美和澳洲后，成为当地强悍的入侵者(因为它们拥有多种强悍的适应能力，各段分类介绍)。
European Green Crab: Tough Survivor重复2016.09.10上午(本年度新题)考句：Certainly green crabs have many of the attributes that seem to be pre requisites for successful invasion, including the ability to rapidly produce la rge numbers of offspring (one female green crab can lay up to 185,000 eggs per clutch and can produce clutches twice a year) and the biological tools needed t o survive the environmental differences from one region to the next.解析：这是文章句子简化题所在句。
托福阅读真题及答案 PASSAGE 2
托福阅读真题及答案 PASSAGE 2选择出guo学习的人数越来越多，参加无疑是进入国外大学的一块敲门砖。
以下是网的关于托福阅读真题及答案：PASSAGE 2，供大家练习备考。
The geology of the Earth's surface is dominated by the particular properties of water. Present on Earth in solid, liquid, and gaseous states, water is exceptionally reactive. It dissolves, transports, and precipitates many chemical pounds and is constantly modifying the face of the Earth.Evaporated from the oceans, water vapor forms clouds, some of which are transported by wind over the continents. Condensation from the clouds provides the essential agentof continental erosion: rain. Precipitated onto the ground, the water trickles down to form brooks, streams, and rivers, constituting what are called the hydrographic work. This immense polarized work channels the water toward a single receptacle: an ocean. Gravity dominates this entire step in the cycle because water tends to minimize its potential energy by running from high altitudes toward the reference point, that is, sea level.The rate at which a molecule of water passes though the cycle is not random but is a measure of the relative sizeof the various reservoirs. If we define residence time asthe average time for a water molecule to pass through oneof the three reservoirs — atmosphere, continent, and ocean— we see that the times are very different. A water molecule stays, on average, eleven days in the atmosphere, one hundred years on a continent and forty thousand yearsin the ocean. This last figure shows the importance of the ocean as the principal reservoir of the hydrosphere but also the rapidity of water transport on the continents.A vast chemical separation process takes places during the flow of water over the continents. Soluble ions such as calcium, sodium, potassium, and some magnesium are dissolved and transported. Insoluble ions such as aluminum, iron, and silicon stay where they are and form the thin, fertile skin of soil on which vegetation can grow. Sometimes soils are destroyed and transported mechanically during flooding. The erosion of the continents thus results from two closely linked and interdependent processes, chemical erosion and mechanical erosion. Their respective interactions and efficiency depend on different factors.1. The word "modifying" in line 4 is closest in meaning to(A) changing(B) traveling(C) describing(D) destroying2. The word "which" in line 5 refers to(A) clouds(B) oceans(C) continents(D) pounds3. Aording to the passage , clouds are primarily formed by water(A) precipitating onto the ground(B) changing from a solid to a liquid state(C) evaporating from the oceans(D) being carried by wind4. The passage suggests that the purpose of the "hydrographic work" (line 8) is to(A) determine the size of molecules of water(B) prevent soil erosion caused by flooding(C) move water from the Earth's surface to the oceans(D) regulate the rate of water flow from streams and rivers5. What determines the rate at which a molecule of water moves through the cycle, as discussed in the third paragraph?(A) The potential energy contained in water(B) The effects of atmospheric pressure on chemical pounds(C) The amounts of rainfall that fall on the continents(D) The relative size of the water storage areas6. The word "rapidity" in line 19 is closest in meaning to(A) significance(B) method(C) swiftness(D) reliability7. The word "they" in line 24 refers to(A) insoluble ions(B) soluble ions(C) soils(D) continents8. All of the following are example of soluble ions EXCEPT(A) magnesium(B) iron(C) potassium(D) calcium9. The word "efficiency" in line 27 is closest in meaning to(A) relationship(B) growth(C) influence(D) effectiveness。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
为了帮助大家高效备考托福，为大家带来托福TPO29阅读Passage2原文文本+题目+答案解析，希望对大家备考有所帮助。
Competition When several individuals of the same species or of several different species depend on the same limited resource,a situation may arise that is referred to as competition.The existence of competition has been long known to naturalists;its effects were described by Darwin in considerable petition among individuals of the same species(intraspecies competition),one of the major mechanisms of natural selection,is the concern of evolutionary petition among the individuals of different species(interspecies competition)is a major concern of ecology.It is one of the factors controlling the size of competing populations,and extreme cases it may lead to the extinction of one of the competing species.This was described by Darwin for indigenous New Zealand species of animals and plants,which died out when competing species from Europe were introduced. 当同一物种的不同个体或不同的物种都依靠同一有限资源时，这种情况往往会引发成所谓的竞争。
竞争的存在已为生物学家们所熟知，其结果也已被达尔文详尽叙述过。
同一物种不同个体之间的竞争(种内竞争)，作为自然选择的一个主要原理，现在属于进化生物学。
不同物种个体之间的竞争(种间竞争)是生态学的主要部分。
它是控制有竞争关系的种群数量的一个因素，而其极端情况可能导致竞争的一方灭绝。
达尔文在描述新西兰本土动植物物种在与引进的欧洲物种的竞争中灭绝时讲到该情况。
No serious competition exists when the major needed resource is in superabundant supply,as in most cases of the coexistence of herbivores(plant eaters).Furthermore,most species do not depend entirely on a single resource,if the major resource for a species becomes scarce,the species can usually shift to alternative resources.If more than one species is competing for a scarce resource,the competing species usually switch to different alternative petition is usually most severe among close relatives with similar demands on the environment.But it may also occur among totally unrelated forms that compete for the same resource,such as seed-eating rodents and ants.The effects of such competition are graphically demonstrated when all the animals or all the plants in an ecosystem come into competition,as happened 2 million years ago at the end of Pliocene,when North and South America became joined by the Isthmus of Panama.North and South American species migrating across the Isthmus now came into competition with each other.The result was the extermination of a large fraction of the South American mammals,which were apparently unable to withstand the competition from invading North American species—although added predation was also an important factor. 当主要需求的资源能充分供给时，竞争就不会很激烈，正如很多情况下植食动物都能够共存。
而且绝大部分物种并不只依靠一种资源，当某物种的主要资源匮乏时，它们常转向其它候选资源。
如果多个物种竞争同一稀缺资源，他们常会转向不同的候选资源。
近亲之间的竞争往往最激烈，因为他们对环境有相似需求。
但激烈竞争也可能发生在毫不相关却需要同一资源的物种之间，例如吃种子的啮齿动物和蚂蚁。
当一个生态系统中的所有动植物都参与到竞争中来时竞争的影响将表现得淋漓尽致，比如在两百万年前上新世末期当南、北美洲在巴拿马地峡处聚拢时所发生的一切。
南、北美洲的物种可以穿越地峡而相互竞争。
结果是大量南美洲哺乳动物因抵抗不了来自北美洲物种的竞争而灭绝----尽管过度捕杀也是一个很重要的因素。
To what extent competition determines the composition of a community and the density of particular species has been the source of considerable controversy.The problem is that competition ordinarily cannot be observed directly but must be inferred from the spread or increase of one species and the concurrent reduction or disappearance of another species.The Russian biologist G.F.Gause performed numerous two-species experiments in the laboratory,in which one of the species became extinct when only a single kind of resource was available.On the basis of these experiments and of field observations,the so-called law of competitive exclusion was formulated,according to which no two species can occupy the same niche.Numerous seeming exceptions to this law have since been found,but they can usually be explained as cases in which the two species,even though competing for a major joint resource,did not really occupy exactly the same niche. 竞争在多大程度上决定群落的组成和某特定物种的密度一直备受争议。
问题是竞争通常无法直接观察得到而必须通过某一物种的扩张或增加而另外一种物种同时减少或消失的对比中推测出来。
俄罗斯生物学家G.F.Gause进行了大量的两物种的室内实验，结果表明当只提供一种资源时其中一个物种将会灭绝。
基于以上实验和实地观察，所谓的竞争灭绝法则是成立的，因为两个物种不可能同时完全占有同一有限资源。
不过也发现了很多例外，但这些情况下两个物种，尽管会争夺某一主要资源，但它们争夺的资源不完全相同。
Competition among species is of considerable evolutionary importance.The physical structure of species competing for resources in the same ecological niche tends to gradually evolve in ways that allow them to occupy different peting species also tend to change their ranges so that their territories no longer overlap.The evolutionary effect of competition on species has been referred to as “species selection”;however,this description is potentially misleading.Only the individuals of a species are subject to the pressures of natural selection.The effect on the well-being and existence of a species is just the result of the effects of selection on all the individuals of the species.Thus species selection is actually a result of individual selection. 物种间的竞争对进化至关重要。