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原文
Evidence of the Earliest Writing
①Although literacy appeared independently in several parts of the prehistoric world,the earliest evidence of writing is the cuneiform Sumerian script on the clay tablets of ancient Mesopotamia,which,archaeological detective work has revealed,had its origins in the accounting practices of commercial activity. Researchers demonstrated that preliterate people,to keep track of the goods they produced and exchanged,created a system of accounting using clay tokens as symbolic representations of their products.Over many thousands of years,the symbols evolved through several stages of abstraction until they became wedge-shaped(cuneiform)signs on clay tablets,recognizable as writing.
②The original tokens(circa8500B.C.E.)were three-dimensional solid shapes—tiny spheres,cones,disks,and cylinders.A debt of six units of grain and eight head of livestock,for example might have been represented by six conical and eight cylindrical tokens.To keep batches of tokens together,an innovation was introduced(circa3250B.C.E.)whereby they were sealed inside clay envelopes that could be broken open and counted when it came time for a debt to be repaid. But because the contents of the envelopes could easily be forgotten,
two-dimensional representations of the three-dimensional tokens were impressed into the surface of the envelopes before they were sealed.Eventually,having two sets of equivalent symbols—the internal tokens and external markings—came to seem redundant,so the tokens were eliminated(circa3250-3100B.C.E.),and only solid clay tablets with two-dimensional symbols were retained.Over time,the symbols became more numerous,varied,and abstract and came to represent more than trade commodities,evolving eventually into cuneiform writing.
③The evolution of the symbolism is reflected in the archaeological record first of all by the increasing complexity of the tokens themselves.The earliest tokens, dating from about10,000to6,000years ago,were of only the simplest geometric shapes.But about3500B.C.E.,more complex tokens came into common usage, including many naturalistic forms shaped like miniature tools,furniture,fruit,and humans.The earlier,plain tokens were counters for agricultural products,whereas the complex ones stood for finished products,such as bread,oil,perfume,wool, and rope,and for items produced in workshops,such as metal,bracelets,types of cloth,garments,mats,pieces of furniture,tools,and a variety of stone and pottery vessels.The signs marked on clay tablets likewise evolved from simple wedges, circles,ovals,and triangles based on the plain tokens to pictographs derived from the complex tokens.
④Before this evidence came to light,the inventors of writing were assumed by researchers to have been an intellectual elite.Some,for example,hypothesized that writing emerged when members of the priestly caste agreed among themselves on written signs.But the association of the plain tokens with the first farmers and of the complex tokens with the first artisans—and the fact that the token-and-envelope accounting system invariably represented only small-scale transactions—testifies to the relatively modest social status of the creators of writing.
⑤And not only of literacy,but numeracy(the representation of quantitative concepts)as well.The evidence of the tokens provides further confirmation that mathematics originated in people’s desire to keep records of flocks and other goods.Another immensely significant step occurred around3100B.C.E.,when Sumerian accountants extended the token-based signs to include the first real numerals.Previously,units of grain had been represented by direct one-to-one correspondence―by repeating the token or symbol for a unit of grain the required number of times.The accountants,however,devised numeral signs distinct from commodity signs,so that eighteen units of grain could be indicated by preceding a single grain symbol with a symbol denoting“18.”Their invention of abstract numerals and abstract counting was one of the most revolutionary advances in the history of mathematics.
⑥What was the social status of the anonymous accountants who produced this
breakthrough?The immense volume of clay tablets unearthed in the ruins of the Sumerian temples where the accounts were kept suggests a social differentiation within the scribal class,with a virtual army of lower-ranking tabulators performing the monotonous job of tallying commodities.We can only speculate as to how high or low the inventors of true numerals were in the scribal hierarchy,but it stands to reason that this laborsaving innovation would have been the brainchild of the lower-ranking types whose drudgery is eased.
译文
最早文字的证据
①虽然读写能力是在史前世界的几个地方分别出现的，但书写的最早证据是古代美索不达米亚泥板上的苏美尔楔形文字，根据考古探查工作揭示，它起源于商业活动的会计实践。

研究人员证明，没有文化的人为了记录他们生产和交换的商品，创造了一种使用粘土代币作为其产品象征的记账系统。

在数千年的时间里，这些符号经历了几个抽象阶段，直到它们变成了粘土上的楔形符号，可被认出是文字。

②最初的代币(约公元前8500年)是三维实体形状——小球体、圆锥体、圆盘和圆柱体。

例如，6个单位的谷物和8头牲畜的债务可以用6个圆锥形和8个圆柱形的代币来表示。

为了把成批的代币放在一起，人们发明了一种新方法（大约在公元前3250年），把代币封在粘土信封里，当需要偿还债务时，粘土信封就会被打开并计数。

但是，由于信封里的东西很容易被遗忘，所以在密封之前，三维代币的二维表现就被印在了信封的表面上。

最终，拥有两套等价的符号——里面的代币和外面的标记——看起来有些冗余，所以代币被淘汰了（大约在公元前3250-3100年），只保留了带有二维符号的固体粘土片。

随着时间的推移，这些符号变得越来越多，越来越多样化，越来越抽象，它们不仅仅代表商品贸易，最终演变成了楔形文字。

③象征符号的演变首先反映在考古记录中，标志本身的复杂性日益增加。

最早的代币大约在10000年到6000年前，只有最简单的几何形状。

大约在公元前3500年，更复杂的代币开始被普遍使用，包括许多像小型工具、家具、水果和人类这样的自然形态。

更早的、简单的代币是为农产品的计数服务的，而复杂的代币用于制成品，如面包、油、香水、羊毛、绳子，和工坊生产的物品，如金属、手镯、布料、服装、垫子、家具、工具、和各种各样的石头和陶瓷器皿。

在粘土片上标记的符号同样也从简单的楔形、圆形、椭圆形和基于简单代币的三角形演变为源自复杂代币的象形文字。

④在这一证据被发现之前，研究人员认为书写的发明者是知识精英。

例如，有些人假设，当祭司种姓的成员对书写符号达成一致时，文字就出现了。

但是简
单代币和早期农民的关联、复杂代币和早期工匠的关联、再加上代币-信封的记账系统总是只代表小规模的交易，这些都是文字创造者的社会地位相对低下的证据。

⑤不仅是读写能力，还有计算能力（定量概念的表示）。

代币的证据进一步证实，数学起源于人们想要记录羊群和其他物品的愿望。

另一个意义重大的进步发生在公元前3100年左右，当时苏美尔人的会计师将基于代币的符号扩展到包含第一个实数。

以前，谷物的单位是由直接的一一对应来表示的——通过重复一单位谷物的代币或符号所需的次数来实现。

然而，会计师们设计了不同于商品符号的数字符号，这样，十八个单位的谷物可以表现为在一个谷物符号前面加上一个表示“18”的符号。

他们发明的抽象数字和抽象计数是数学历史上最具革命性的进步之一。

⑥促成这一突破的匿名会计师的社会地位如何?苏美尔庙宇遗址中出土的数量巨大的粘土片显示了抄写文字方面的社会分化，实际上是一群等级较低的制表人在从事单调的商品清点工作。

我们只能推测出真正数字的发明者在抄写阶层中的地位有多高或多低，但显而易见的是，这种节省劳力的发明是那些地位较低的人的智慧结晶，他们的苦工因此得以减轻。

题目
1.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage?Incorrect choices change the meaning in important ways or leave out essential information.
A.Sumerian script,the earliest known form of writing among prehistoric writing systems,was first used on clay tablets for accounting purposes.
B.Although the earliest Sumerians engaged in commercial activity and practiced accounting,they were not as literate as people in other parts of the prehistoric world.
C.Archaeologists have discovered that literacy was developed in several parts of the world,including ancient Mesopotamia.
D.Archaeological detective work has revealed the commercial accounting practices of the Sumerians of ancient Mesopotamia and provided a written record of their intense commercial activity.
①Although literacy appeared independently in several parts of the prehistoric world,the earliest evidence of writing is the cuneiform Sumerian script on the clay
tablets of ancient Mesopotamia,which,archaeological detective work has revealed,had its origins in the accounting practices of commercial activity. Researchers demonstrated that preliterate people,to keep track of the goods they produced and exchanged,created a system of accounting using clay tokens as symbolic representations of their products.Over many thousands of years,the symbols evolved through several stages of abstraction until they became wedge-shaped(cuneiform)signs on clay tablets,recognizable as writing.
2.All of the following are mentioned in paragraph2as true of clay envelopes EXCEPT:
A.They contained batches of tokens.
B.They could be reused frequently.
C.They had markings on the outside.
D.They could be used to record debts.
3.According to paragraph2,the first two-dimensional symbols were
A.pictures of commodities drawn on clay tablets
B.images sealed inside conical or cylindrical containers
C.numbers used for keeping track of clay envelopes
D.images of tokens pressed into the clay of envelopes
4.According to paragraph2,why were tokens eliminated?
A.They were not numerous or varied enough to represent all of the trade commodities.
B.They were easily broken and then hard to count.
C.They were difficult to keep together in batches.
D.They were unnecessary when symbols were used on the surface of envelopes.
5.Which of the following can be inferred from paragraph3about the difference between earlier tokens and later tokens?
ter tokens were made of many different materials,but earlier ones were
made only of clay.
ter tokens often looked like the commodities that they represented,but earlier ones did not.
ter tokens represented agricultural products,but earlier ones represented finished products.
ter tokens were based on pictographs，but earlier ones were based on naturalistic forms.
6.The word“likewise"in the passage is closest in meaning to
A.probably
ually
C.similarly
D.apparently
7.The word“Some”in the passage refers to
A.evidence
B.inventors
C.researchers
D.intellectual elite
8.In paragraph4,why does the author mention the association of tokens with farmers and artisans?
A.To provide examples of the types of commercial activity that existed in Sumerian society
B.To argue against the theory that writing was developed by an intellectual elite
C.To contrast the way farmers used tokens with the way artisans used tokens
D.To help explain why farmers and artisans had a relatively modest social status in Sumerian society
9.The word“invariably”in the passage is closest in meaning to
A.easily
B.accurately
C.always
D.soon
10.According to paragraph5,all of the following statements about the development of numerals are true EXCEPT:
A.Numerals first developed around3100
B.
C.E.
B.Numerals were created to keep records of commodities.
C.The numeral“18”developed from the sign for grain.
D.Accountants introduced unique numeral signs for use with signs for commodities.
11.The word“unearthed”in the passage is closest in meaning to
A.discovered
B.protected
C.buried
D.forgotten
12.The word“brainchild"in the passage is closest in meaning to
A.symbol
B.concern
C.pride
D.invention
13.Look at the four squares[■]to add the sentence to the passage.
Such a system was clearly awkward for large inventories..
⑤And not only of literacy,but numeracy(the representation of quantitative concepts)as well.The evidence of the tokens provides further confirmation that mathematics originated in people’s desire to keep records of flocks and other goods.Another immensely significant step occurred around3100B.C.E.,when Sumerian accountants extended the token-based signs to include the first real numerals.[■]Previously,units of grain had been represented by direct one-to-one correspondence―by repeating the token or symbol for a unit of grain the required number of times.[■]The accountants,however,devised numeral signs distinct from commodity signs,so that eighteen units of grain could be indicated by preceding a single grain symbol with a symbol denoting“18.”[■]Their invention of abstract numerals and abstract counting was one of the most revolutionary advances in the history of mathematics.[■]
14.Directions:An introductory sentence for a brief summary of the passage is provided plete the summary by selecting the THREE answer choices that express the most important ideas in the passage.Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage.This question is worth2points.Drag your answer choices to the spaces where they belong.To remove an answer choice, click on it.To review the passage,click VIEW TEXT.Over a period of thousands of years,the symbols originally used for keeping track of goods evolved into the first writing system,Sumerian cuneiform.
A.Three-dimensional tokens used to keep track of debts of grain and livestock eventually gave way to two-dimensional symbols on clay tablets.
B.Writing was probably developed by farmers and artisans,since the symbols were first used to keep track of agricultural products and items produced by artisans.
C.Two separate sets of symbols were used to keep track of each accounting of goods to avoid mistakes in the accounting when only one set of tokens or marks was used.
D.Early tokens representing three-dimensional geometric shapes show that ancient Mesopotamians invented geometry as well as writing.
E.The inventors of numerals were probably lower-ranking accountants because they were assigned the job of developing new methods of accounting for large inventories.
F.Symbols were first used in a direct one-to-one correspondence with the commodity being counted,but eventually true numerals were developed.
答案
1-5.A B D D B
6-10.C C B C C
11-13.A D B
14.ABF
小结题解析
【题目翻译】说明：下面是文章的简要概括的介绍句。

通过选择三个答案来完成总结，这三个答案表达了文章中最重要的观点。

有些句子不属于摘要，因为它们表达了文章中没有呈现的想法，或者是文章中的次要思想。

在几千年的时间里，最初用来追踪商品的符号演变成了第一个书写系统，苏美尔楔形。

A：用来记录谷物和牲畜债务的三维符号最终被粘土片上的二维符号所取代。

B：文字可能是由农民和工匠发展起来的，因为符号最初是用来跟踪农产品和工匠生产的物品。

职员：两套独立的符号用来记录货物的每个记账，以避免在只使用一套记号或记号时出现记账错误。

D：早期代表三维几何形状的符号表明古代美索不达米亚人发明了几何和书写。

E：数字的发明者可能是低阶的会计师，因为他们被分配了开发大型存货的新会计方法的工作。

F：符号最初是用于与被计数的商品直接一对一的对应关系，但最终产生了真正的数字。

【判定题型】：根据问题的提问方式和6选3的作答方式可以确定该题目为概要小结题。

【选项定位及分析】
选项A正确概括了第二段的主要内容，正确；
选项B正确概括了第四段的主要内容，正确；
选项C的意思是为了避免使用一套系统导致的错误，计数的时候要使用两套不同的系统，不符合文意，错误；
选项D的意思是早期的几何符号意味着苏美尔人不仅发明了文字，还发明了几何学，无中生有，不选；
选项E说数字的发明者是低阶级的会计，这是倒数第二段的一处细节信息，故不选。

选项F正确概括了第五段的主要内容，正确。

背景知识
世界上最早的文字是哪种？
关于世界上最早的文字，这是一个备受争议的话题。

在考古学和语言学领域，专家们一直在努力寻找证据来揭示这个谜团。

虽然目前没有确凿的证据可以确定哪种文字是最早出现的，但是通过对历史文献和考古发现的综合分析，我们可以得到一些有意义的结论。

最早的文字：象形文字
根据目前所知的历史记录和考古发现，人类最早使用的文字应该是象形文字。

象形文字是指用图画来表示事物或概念的一种书写方式。

例如，在中国古代，人们用“日”来表示太阳，“山”来表示山脉，“水”来表示水流等等。

在远古时期，人们还不具备抽象思维能力，他们只能通过视觉上的印象来表达自己想要传达的信息。

因此，他们开始将简单、易于辨认的图画作为一种通信工具，并逐渐演变成了象形文字。

当然，在不同地区和文明中出现了不同类型、风格和特点各异的象形文字。

比如，在埃及文明中出现了著名的“金字塔文”，而在美索不达米亚文明中则出现了“楔形文字”。

其他可能的最早文字
除了象形文字之外，还有一些其他的可能是最早出现的文字。

这些包括：
线性A和B文字：线性A和B文字是在克里特岛上发现的两种古代书写系统。

它们分别于1900年和1952年被发现，但到目前为止，仍然没有人能够解读它们。

印度河谷文明的印度-布拉姆文：印度-布拉姆文是在印度河流域发现的一种古代书写系统。

它约于公元前3000年左右出现，并被广泛用于印度河谷文明。

中国甲骨文：甲骨文是中国商代时期（公元前1600年-公元前1046年）使用的一种古代书写系统。

它是通过在龟甲和兽骨上刻画图案来表达意思。

古巴比伦楔形文字：古巴比伦楔形文字是古巴比伦王国使用的一种书写方式。

它约于公元前2000年左右出现，并成为了美索不达米亚地区广泛使用的一种书写方式。

虽然我们不能确定哪种文字是最早出现的，但是通过对历史文献和考古发现的综合分析，我们可以得到一些有意义的结论。

首先，无论哪种文字是最早出现的，都必须具备以下特点：易于书写、易于辨认、易于传播。

其次，随着人类社会的不断发展和进步，各种文字也在不断演变和改进。

因此，在考虑哪种文字是最早出现的时候，我们也必须考虑它们在历史上所扮演的角色以及它们对人类社会发展的影响。

总之，寻找世界上最早的文字仍然是一个充满争议和挑战性的话题。

尽管我们可能永远无法确定确切答案，但通过深入研究人类历史和语言学知识，我们可以更好地理解人类文明的起源和演变。

阅读-2
原文
Rain Forest Soils
①On viewing the lush plant growth of a tropical rain forest,most people would conclude that the soil beneath it is rich in nutrients.However,although rain forest soils are highly variable,they have in common the fact that abundant rainfall washes mineral nutrients out of them and into streams.This process is known as leaching.Because of rain leaching,most tropical rain forest soils have low to very low mineral nutrient content,in dramatic contrast to mineral-rich grassland soils. Tropical forest soils also often contain particular types of clays that,unlike the mineral-binding clays of temperate forest soils,do not bind mineral ions well. Aluminum is the dominant cation(positively charged ion)present in tropical soils; but plants do not require this element,and it is moderately toxic to a wide range of
plants.Aluminum also reduces the availability of phosphorus,an element in high demand by plants.
②High moisture and temperatures speed the growth of soil microbes that decompose organic compounds,so tropical soils typically contain far lower amounts of organic materials(humus)than do other forest or grassland soils. Because organic compounds help loosen compact clay soils,hold water,and bind mineral nutrients,the relative lack of organic materials in tropical soils is deleterious to plants.Plant roots cannot penetrate far into hard clay soils,and during dry periods,the soil cannot hold enough water to supply plant needs. Because the concentration of dark-colored organic materials is low in tropical soils, they are often colored red or yellow by the presence of iron,aluminum:and manganese oxides;when dry,these soils become rock hard.The famous Cambodian temples of Angkor Wat,which have survived for many centuries,were constructed from blocks of such hard rain forest soils.
③Given such poor soils,how can lush tropical forests exist?The answer is that the forest's minerals are held in its living biomass—the trees and other plants and the animals.In contrast to grasslands,where a large proportion of plant biomass is produced underground,that of tropical forests is nearly all aboveground.Dead leaves,branches,and other plant parts,as well as the wastes and bodies of rain forest animals,barely reach the forest floor before they are rapidly decayed by abundant decomposers—bacterial and fungal.Minerals released by decay are quickly absorbed by multitudinous shallow,fine tree feeder roots and stored in plant tissues.Many tropical rain forest plants(like those in other forests)have mycorrhizal(fungus-root)partners whose delicate hyphae spread through great volumes of soil,from which they release and absorb minerals and ferry them back to the host plant in exchange for needed organic compounds.The fungal hyphae are able to absorb phosphorus that plant roots could not themselves obtain from the very dilute soil solutions,and fungal hyphae can transfer mineral nutrients from one forest plant to another.Consequently,tropical rain forests typically have what are known as closed nutrient systems,in which minerals are handed off from one organism to another with little leaking through to the soil.When mineral nutrients do not spend much time in the soil,they cannot be leached into streams. Closed nutrient systems have evolved in response to the leaching effects of heavy tropical rainfall.Evidence for this conclusion is that nutrient systems are more open in the richest tropical soils and tightest in the poorest soils.
④The growth of organisms is dependent on the availability of nutrients,none of which is more important than nitrogen.Although there is an abundant supply of nitrogen in Earth’s atmosphere,it cannot be absorbed by plants unless it is“fixed,”or combined chemically with other elements to form nitrogen compounds. Nitrogen-fixing bacteria help tropical rain forest plants cope with the poor soils there by supplying them with needed nitrogen.Many species of tropical rain forest
trees belong to the legume family,which is known for associations of nitrogen-fixing bacteria within root nodules.Also,cycads(a type of tropical plant that resembles a palm tree)produce special aboveground roots that harbor nitrogen-fixing cyanobacteria.By growing above the ground,the roots are exposed to sunlight,which the cyanobacteria require for growth.Nitrogen fixation by free-living bacteria in tropical soils is also beneficial.
译文
热带雨林土壤
①在观察热带雨林茂盛的植物生长时，大多数人会得出这样的结论：雨林下面的土壤营养丰富。

然而，尽管雨林土壤变化很大，但它们都有一个共同的事实，那就是大量的降雨将矿物质养分冲出土壤，流入河流。

这个过程称为浸出。

由于雨水浸出作用，大多数热带雨林土壤的矿物养分含量不是低就是极低，这种情况与富含矿物的草原土壤形成了鲜明的对比。

热带森林土壤也经常含有特殊类型的粘土，不像温带森林土壤的矿物结合粘土，它们不能很好地让矿物离子结合。

铝是热带土壤中的主要阳离子（带正电荷的离子）；但植物不需要这种元素，而且它对多种植物有中度毒性。

铝还会减少磷的供应，而磷是植物需求量很大的一种元素。

②较高的湿度和温度提升了分解有机化合物的土壤微生物的生长速度，因此热带土壤通常比其他森林或草原土壤含有的有机物质(腐殖质)要少得多。

由于有机化合物对于疏松致密的粘土，保持水分和结合矿物养分都能起到帮助，所以热带土壤中相对缺乏有机物质的情况对植物是有害的。

植物根系不能深入硬粘土，在干旱时期，土壤不能保持足够的水分来满足植物的需要。

由于深色有机物质在热带土壤中的浓度较低，它们常因铁、铝和锰氧化物的存在而呈红色或黄色；当干燥时，这些土壤就会变得如岩石般坚硬。

柬埔寨著名的吴哥窟寺庙，已经存在了许多世纪，它是由这样坚硬的雨林土壤建造的。

③鉴于如此贫瘠的土壤，茂盛的热带森林怎么可能存在呢?答案是，森林里的矿物质存在于它的生物群落中——树木、其他植物和动物。

与大比例植物生物量产生于地下的草地不同，热带森林的草地几乎都是地上的。

枯叶、枯枝和其他植物部分，以及热带雨林动物的废物和尸体，在被大量的分解者——细菌和真菌——迅速腐烂之前，几乎不能到达森林地面。

腐烂释放出的矿物质被众多浅而细的树根迅速吸收，并储存在植物组织中。

许多热带雨林植物（和其他森林一样）都有菌根（真菌根）伙伴，它们脆弱的菌丝散布在大量的土壤中，它们从土壤中释放和吸收矿物质，并将它们运送回寄主植物，以换取所需的有机化合物。

真菌菌丝能吸收植物根系自身无法从极稀的土壤溶液中获得的磷，且其能够将矿物养分从一种森林植物转移至另一种森林植物。

因此，热带雨林一般有着被称作封闭营养系统的东西，在这个系统中，矿物质从一个生物体传递
到另一个生物体，很少渗入土壤。

当矿物质营养物质在土壤中停留的时间不长时，它们就不能被过滤到溪流中。

由于热带强降雨的浸出作用，已形成封闭的营养系统。

这一结论的证据是，营养系统在最肥沃的热带土壤中更开放，而在最贫瘠的土壤中更紧密。

④生物体的生长依赖于营养物质的供应，而营养物质中没有一种比氮更重要。

尽管地球大气中有丰富的氮供应，但除非被“固定”，或与其他元素化学结合形成氮化合物，否则植物无法吸收氮。

固氮细菌为热带雨林植物提供所需的氮，帮助它们应对贫瘠的土壤。

热带雨林中的许多树种属于豆科植物，这种植物以根瘤内固氮细菌的组合而出名。

此外，苏铁（一种类似棕榈树的热带植物）产生特殊的地上根，其中含有固氮蓝藻。

通过在地上生长，根暴露在阳光下，这是蓝藻生长所需要的。

生长在热带土壤中的自由生活细菌所带来的固氮同样是有益的。

题目
1.Select the TWO answer choices that,according to paragraph1,help explain the relatively low mineral nutrient content of most tropical rain forest soils.To receive credit,you must select TWO answers
A.The water in the streams flowing through tropical rain forests generally has relatively low mineral content.
B.The range of plants that grow in tropical rain forests is so wide that almost every kind of mineral in the soil gets used up.
C.The clays contained in tropical rain forest soils do not bind mineral ions well.
D.Abundant rainfall causes minerals to leach out of the soil.
2.According to paragraph1,one reason that the relatively high levels of aluminum in rain forest soils present a problem for plants is that aluminum
A.reduces the mineral-binding capacity of soils
B.is somewhat toxic to plants
C.makes too much phosphorus available to plants
D.is present as a positively charged ion in tropical rain forest soils
3.According to paragraph2,clay soils that contain relatively low amounts of organic materials have all of the following disadvantages for plants EXCEPT
A.poor water retention
B.poor root penetrability
C.few soil microbes
D.low levels of mineral nutrients
4.Paragraph2supports the idea that,as compared with rain forest soils,grassland soils
A.contain a greater variety of soil microbes
B.contain less organic material
C.are able to hold more water
D.are generally lighter colored
5.Why does the author mention"Angkor Wat"?
A.To show that rain forest soils are essentially the same today as they were many centuries ago
B.To make the point that rain forest soils have certain advantages over other types of soils
C.To illustrate how colorful rain forest soils can sometimes be
D.To emphasize how hard rain forest soils can become
6.Paragraph2suggests the idea that compared with grassland soils,tropical rain forest soils have all of the following characteristics EXCEPT
A.soil microbes grow more slowly
B.contain lower amounts of organic materials
C.hold less water
D.contain iron,aluminum and manganese oxides
7.The word"multitudinous"in the passage is closest in meaning to
A.a great many
B.rapidly increasing
C.finely divided
D.extremely strong
8.The word“Consequently”in the passage is closest in meaning to
A.Nevertheless
B.However
C.As a result
D.In addition
9.According to paragraph3,the main advantage of a closed nutrient system is that such a system
A.reduces the risk of minerals being lost through leaching
B.ensures that all organisms in the system receive an adequate supply of nutrients
C.increases the amount of nutrients that plant roots can absorb from soil solutions
D.increases the speed with which nutrients are returned to the soil
10.The word“abundant”in the passage is closest in meaning to
A.valuable
B.plentiful
able
D.obvious
11.According to paragraph4,why can getting enough nitrogen be a problem for plants?
A.Because most of Earth’s nitrogen is located in the atmosphere
B.Because plants can use the nitrogen they absorb only if they have previously absorbed certain other elements that are often scarce in poor soils
C.Because plants cannot absorb nitrogen that has not been chemically combined with other elements
D.Because plants have to compete with bacteria for available nitrogen in the soil
12.Paragraph4supports the idea that having aboveground roots benefits cycads in which of the following ways?
A.By increasing the growth rate of cycads'roots through exposure to sunlight
B.By increasing the supply of usable nitrogen available to cycads
C.By reducing the amount of nitrogen cycads require
D.By reducing cycads’dependence on nitrogen-fixing bacteria
13.Look at the four squares[■]to add the sentence to the passage.
In many contexts—grasslands and most other types of forest,for example—that inference would be correct..
①On viewing the lush plant growth of a tropical rain forest,most people would conclude that the soil beneath it is rich in nutrients.[■]However,although rain forest soils are highly variable,they have in common the fact that abundant rainfall washes mineral nutrients out of them and into streams.[■]This process is known as leaching.[■]Because of rain leaching,most tropical rain forest soils have low to very low mineral nutrient content,in dramatic contrast to mineral-rich grassland soils.[■]Tropical forest soils also often contain particular types of clays that, unlike the mineral-binding clays of temperate forest soils,do not bind mineral ions well.Aluminum is the dominant cation(positively charged ion)present in tropical soils;but plants do not require this element,and it is moderately toxic to a wide range of plants.Aluminum also reduces the availability of phosphorus,an element in high demand by plants.
14.Directions:An introductory sentence for a brief summary of the passage is provided plete the summary by selecting the THREE answer choices that express the most important ideas in the passage.Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage.This question is worth2points.Drag
your answer choices to the spaces where they belong.To remove an answer choice, click on it.To review the passage,click VIEW TEXT.Although tropical rain forest plants grow vigorously,the clay soils of tropical rain forests are very low in mineral nutrients.
A.Clays with poor mineral-binding capacities plus low levels of organic compounds that result from rapid decomposition produce compacted soils that are highly vulnerable to rain leaching.
B.Plants are able to tolerate the high levels of aluminum in tropical rain forest soils only because of bacteria and fungi that neutralize aluminum while absorbing and transferring phosphorus.
C.Because water does not penetrate deep into tropical rain forest soils,most trees growing in such soils have shallow feeder roots that spread over large areas in search of adequate moisture.
D.The delicate fungal hyphae that extend throughout most tropical rain forest soil help maintain soil quality by transferring excess nutrients from plant tissues back into the soil.
E.Tropical rain forests have evolved closed nutrient systems,in which plants and their fungal partners transfer mineral nutrients among organisms with little leaching through to the soil.
F.Nitrogen-fixing bacteria in the soil and within the roots and root nodules of many plants provide rain forest plants with the nitrogen needed to help compensate for poor soils.
答案
1-5.CD B C C D
6-10.A A C A B
11-13.C B A
14.AEF。