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1、 为了帮助大家高效备考托福，为大家带来托福 TPO3 阅读 Passage3 原文文本+题目+答案 解析，希望对大家备考有所帮助。 托福 TPO3 阅读 Passage3 原文文本： The Long-Term Stability of Ecosystems Plant communities assemble themselves flexibly, and their particular structure depends on the specific history of the area. Ecologists use the term “succession” to refer
2、to the changes that happen in plant communities and ecosystems over time. The first community in a succession is called a pioneer community, while the long- lived community at the end of succession is called a climax community. Pioneer and successional plant communities are said to change over perio
3、ds from 1 to 500 years. These changesin plant numbers and the mix of speciesare cumulative. Climax communities themselves change but over periods of time greater than about 500 years. An ecologist who studies a pond today may well find it relatively unchanged in a years time. Individual fish may be
4、replaced, but the number of fish will tend to be the same from one year to the next. We can say that the properties of an ecosystem are more stable than the individual organisms that compose the ecosystem. At one time, ecologists believed that species diversity made ecosystems stable. They believed
5、that the greater the diversity the more stable the ecosystem. Support for this idea came from the observation that long-lasting climax communities usually have more complex food webs and more species diversity than pioneer communities. Ecologists concluded that the apparent stability of climax ecosy
6、stems depended on their complexity. To take an extreme example, farmlands dominated by a single crop are so unstable that one year of bad weather or the invasion of a single pest can destroy the entire crop. In contrast, a complex climax community, such as a temperate forest, will tolerate considera
7、ble damage from weather to pests. The question of ecosystem stability is complicated, however. The first problem is that ecologists do not all agree what “stability” means. Stability can be defined as simply lack of change. In that case, the climax community would be considered the most stable, sinc
8、e, by definition, it changes the least over time. Alternatively, stability can be defined as the speed with which an ecosystem returns to a particular form following a major disturbance, such as a fire. This kind of stability is also called resilience. In that case, climax communities would be the m
9、ost fragile and the least stable, since they can require hundreds of years to return to the climax state. Even the kind of stability defined as simple lack of change is not always associated with maximum diversity. At least in temperate zones, maximum diversity is often found in mid-successional sta
10、ges, not in the climax community. Once a redwood forest matures, for example, the kinds of species and the number of individuals growing on the forest floor are reduced. In general, diversity, by itself, does not ensure stability. Mathematical models of ecosystems likewise suggest that diversity doe
11、s not guarantee ecosystem stabilityjust the opposite, in fact. A more complicated system is, in general, more likely than a simple system to break down. A fifteen-speed racing bicycle is more likely to break down than a childs tricycle. Ecologists are especially interested to know what factors contr
12、ibute to the resilience of communities because climax communities all over the world are being severely damaged or destroyed by human activities. The destruction caused by the volcanic explosion of Mount St. Helens, in the northwestern United States, for example, pales in comparison to the destructi
13、on caused by humans. We need to know what aspects of a community are most important to the communitys resistance to destruction, as well as its recovery. Many ecologists now think that the relative long-term stability of climax communities comes not from diversity but from the “patchiness” of the en
14、vironment, an environment that varies from place to place supports more kinds of organisms than an environment that is uniform. A local population that goes extinct is quickly replaced by immigrants from an adjacent community. Even if the new population is of a different species, it can approximatel
15、y fill the niche vacated by the extinct population and keep the food web intact. 托福 TPO3 阅读 Passage3 题目： Question 1 of 14 The word “particular ” in the passage is closest in meaning to A. natural. B. final. C. specific. D. complex. Question 2 of 14 According to paragraph 1, which of the following is
16、 NOT true of climax communities? A. They occur at the end of a succession B. They last longer than any other type of community C. The numbers of plants in them and the mix of species do not change D. They remain stable for at least 500 years at a time Question 3 of 14 According to paragraph 2, which
17、 of the following principles of ecosystems can be learned by studying a pond? A. Ecosystem properties change more slowly than individuals in the system B. The stability of an ecosystem tends to change as individuals are replaced C. Individual organisms are stable from one year to the next D. A chang
18、e in the members of an organism does not affect an ecosystems properties Question 4 of 14 According to paragraph 3, ecologists once believed that which of the following illustrated the most stable ecosystems? A. Pioneer communities. B. Climax communities. C. Single-crop farmlands. D. Successional pl
19、ant communities. Question 5 of 14 According to paragraph 4, why is the question of ecosystem stability complicated? A. The reasons for ecosystem change are not always clear. B. Ecologists often confuse the word “stability” with the word “resilience.”. C. The exact meaning of the word “stability” is
20、debated by ecologists D. There are many different answers to ecological questions Question 6 of 14 According to paragraph 4, which of the following is true of climax communities? A. They are more resilient than pioneer communities B. They can be considered both the most and the least stable communit
21、ies C. They are stable because they recover quickly after major disturbances D. They are the most resilient communities because they change the least over time Question 7 of 14 Which of the following can be inferred from paragraph 5 about redwood forests? A. They become less stable as they mature B.
22、 They support many species when they reach climax C. They are found in temperate zones D. They have reduced diversity during mid-successional stages Question 8 of 14 The word “guarantee ” in the passage is closest in meaning to A. increase. B. ensure. C. favor. D. complicate. Question 9 of 14 In par
23、agraph 5, why does the author provide the information that “A fifteen-speed racing bicycle is more likely to break down than a childs tricycle ”? A. To illustrate a general principle about the stability of systems by using an everyday example. B. To demonstrate that an understanding of stability in
24、ecosystems can be applied to help understand stability in other situations. C. To make a comparison that supports the claim that, in general, stability increases with diversity. D. To provide an example that contradicts mathematical models of ecosystems. Question 10 of 14 The word “pales ” in the pa
25、ssage is closest in meaning to A. increases proportionally. B. differs. C. loses significance. D. is common. Question 11 of 14 Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incurred choices change the meaning in important ways or le
26、ave out essential information. A. Ecologists now think that the stability of an environment is a result of diversity rather than patchiness B. Patchy environments that vary from place to place do not often have high species diversity C. Uniform environments cannot be climax communities because they
27、do not support as many types of organisms as patchy environments D. A patchy environment is thought to increase stability because it is able to support a wide variety of organisms Question 12 of 14 The word “adjacent ” in the passage is closest in meaning to A. foreign. B. stable. C. fluid. D. neigh
28、boring. Question 13 of 14 Look at the four squares that indicate where the following sentence could be added to the passage. Where would the sentence best fit?. In fact, damage to the environment by humans is often much more severe than damage by natural events and processes Question 14 of 14 Direct
29、ions: 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 p
30、assage or are minor ideas in the passage. This question is worth 2 points.The process of succession and the stability of a climax community can change over time. . A.The changes that occur in an ecosystem from the pioneer to the climax community can be seen in one human generation B.A high degree of
31、 species diversity does not always result in a stable ecosystem C.Disagreements over the meaning of the term “stability“ make it difficult to identify the most stable ecosystems D.Ecologists agree that climax communities are the most stable types of ecosystems E.The level of resilience in a plant co
32、mmunity contributes to its long-term stability F.The resilience of climax communities makes them resistant to destruction caused by humans 托福 TPO3 阅读 Passage3 答案解析： Question 1 of 14 正确答案：C 题目解析 ： C particular: 特别的，特定的。A 是自然地;B 是最终地;C 是特定的;D 是复 杂 的 。 根 据 词 意 ， 答 案 是 C 的 specific。 对 应 原 文 Plant commun
33、ities assemble themselves flexibly, and their particular structure depends on the specific history of the area.前文说 assemble them flexibly， 多变的， 就是每个群落都不一样， 强调特殊性。 而且后半句话说了particular的结构取决于specific的历史， particular和specific呼应， 因此答案很明显是 C。 Question 2 of 14 正确答案：C 题目解析：B 以 climax communities 做关键词定位至原文第三句和
34、最后一句： The first community in a succession is called a pioneer community, while the long-lived community at the end of succession is called a climax community. Climax communities themselves change but over periods of time greater than about 500 years.第三句说明 A 对， 不选;最后一句说明D对， 不选;B没直说， 说其他communities变化周
35、期在1-500年， climax 最少是 500 年，说明 climax 比较长，B 对，不选。而且最后一句也说了 climax 是变化的，C 说反了，选。 Question 3 of 14 正确答案：A 题目解析：A, 本段非常短，迅速看完之后发现最后一句是结论： We can say that the properties of an ecosystem are more stable than the individual organisms that compose the ecosystem.说生态系统比组成生态系统的任意单一物种都稳定， A 是答案。 其他三个选项 都未提及。 Qu
36、estion 4 of 14 正确答案：B 题目解析 ： B 以 ecologists 做关键词定位至本段第一二句，说生态学家认为生态系统中 物种越多越稳定。接着在举例子的时候作者举到了 climax communities： They believed that the greater the diversity the more stable the ecosystem. Support for this idea came from the observation that long-lasting climax communities usually have more complex
37、 food webs and more species diversity than pioneer communities.说明生态学家认 为 climax communities 最稳定，答案 B。 Question 5 of 14 正确答案：C 题目解析：C 以 question of ecosystem stability 为关键词定位至本段头两句： The first problem is that ecologists do not all agree what “stability“ means.说生态学家对 于什么是生态系统的稳定性依然存在争议，C 是原文的忠实改写。 Ques
38、tion 6 of 14 正确答案：B 题目解析：B 关于 climax communities 原文有两个地方提到： In that case, the climax community would be considered the most stable, since, by definition, it changes the least over time. In that case, climax communities would be the most fragile and the least stable, since they can require hundreds o
39、f years to return to the climax state.因为生态学家对什么是稳定的定义存在两个观点：以不变这种观点看，climax 是最稳 定的;以快速恢复这种观点看，climax 是最不稳定的，所以 climax 既稳定也不稳定。B 明确 说到两个方面，其它选项都只说到一个方面。 Question 7 of 14 正确答案：C 题目解析 ： C 以 redwood forest 做关键词定位至原文第三句，事实上这个 redwood 是前 句的一个具体例子： At least in temperate zones, maximum diversity is often fo
40、und in mid-successional stages, not in the climax community.前面句说至少在温带， mid 是最稳 定的，不是 climax，紧接着就举了一个 redwood 的例子，可以推断 redwood 是温带植物，C 是答案。A/B/D 都与原文意思相反，而且 B 和 D 基本上意思一样，都不对。 Question 8 of 14 正确答案：B 题目解析 ： B guarantee: 保证， 确保。 A 是增加;B 是确保;C 是赞成， 喜欢;D 是使复杂。 根据词意，B 是正确答案。对应原文 Mathematical models of ec
41、osystems likewise suggest that diversity does not guarantee ecosystem stabilityjust the opposite, in fact.本 句中有个 likewise，说明它与前面句子构成类比，前句说 diversity does not ensure stability, 后文的内容几乎和前句一模一样， 除了动词被替换， 因此 guarantee 的意思就是 ensure。 Question 9 of 14 正确答案：A 题目解析：A 括号的作用是解释括号之前的文字： A more complicated syste
42、m is, in general, more likely than a simple system to break down.前文说系统越复杂越容易坏，后 面举了十五速赛车和小孩子的三轮车的例子， 三轮车明显比赛车简单， 所以就是支持前文， A 正确，C 正好说反，其他都没说。 Question 10 of 14 正确答案：C 题目解析 ： C pale: 苍白， 使失色。 A 是成比例增长;B 是不同;C 是失去重要性;D 是常见， 普通。根据词意，C 是正确答案。对应原文 The destruction caused by the volcanic explosion of Mount
43、 St. Helens, in the northwestern United States, for example, pales in comparison to the destruction caused by humans.单词所在句之前说很多 climax communities 都被人类破坏了，也就是强调人的破话很严重。后面举了个例子，说圣海伦斯 火山爆发造船的破坏还没有人类活动的破坏严重，所以 C 选项 lose significance 正确。 Question 11 of 14 正确答案：D 题目解析：D : 原文的结构是生态系统的长期稳定性不是因为 diversity，而
44、是因为 patchiness，又对这个进行了解释，说物种多。A 说反;B 错，因为原文没有说 patchiness 和 diversity 是矛盾的;C 错，因为原文比较的是 patchiness 和 uniform，而 C 直接将 patchiness 和 climax 进行比较，偷换概念;D 正确，注意原文貌似没有明显的因果关系，因 此可能单看句子间关系的话会排除 D，但原文后半句整个是对 patchiness 的一种解释，所以 存在不明显的因果关系。 Question 12 of 14 正确答案：D 题目解析：D，adjacent: 相邻。A 是外国的;B 是稳定的;C 是流动的;D 是
45、相邻的。根据 词意，D 是正确答案。对应原文 A local population that goes extinct is quickly replaced by immigrants from an adjacent community.原文说本地的 population 灭绝的话会被哪里来 的群落补充，可能的只有 foreign 和 neighboring，这两个选项代入原文都是可以的，除知 道这个单词的意思之外， 还可以认为相邻的群落更有可能迅速补充， 而外来的范围太大， 不对。 Question 13 of 14 正确答案：B 题目解析：B 根据待插入句中的 human 判断，A/B
46、/C 是可能的，natural events and processes 自然的过程，与第二句中的圣海伦斯火山爆发是同义替换，所以 B/C 可能正确， 但按照先理论后实例的原则，正确答案是 B 不是 C。 Question 14 of 14 正确答案：BCE 题目解析：B.C.E The changes 选项与原文首段的最后一句意思相反，不选。A high degree 选项对应原文第三段和第五段的首句，第四段的最后一句，正确。The level 选项对 应原文第六段首句，第四段倒数第二第三句，正确。Ecologists 选项与原文第三段第四段的 首句意思相反，不选。Disagreements 选项对应原文第四段第二句，正确。The resilience 选项原文没说，原文第六段说不知道为什么生物群落能抵抗破坏，不选。 以上是给大家整理的托福 TPO3 阅读 Passage3 原文文本+题目+答案解析，希望对你有所 帮助!