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托福阅读复习的四个建议
1. 如果基础一般的同学，想要参加托福考试，最好提前3-4个月准备起来。一本好的词汇书是必不可少的。其实背哪一本词汇书不是重点所在，重要的是能够持之以恒，每天对所背的词汇进行复习和总结。因为你在做词汇题时如果能遇到你熟悉的词，可以节省你会到文章中去看上下文猜词的时间。虽然不能保证背到就一定能考到，但是单词可以帮助你更好的理解文章。曾经有一名语言专家这样说过：“Without grammar, little can be conveyed and without vocabulary, nothing can be conveyed.”足以说明词汇的重要性。 2. 然后要从理解文章的结构开始理解文章。我们要明白，托福考试的阅读文章都是北美校园基础课程的文章，基本没有做过改动。所以文章的结构就是完全按照美式作文的五段法，我们的考生只要用这样的方式去分析每一篇文章，就会发现他们的结构是大同小异的。 3. 积累背景知识对我们来说相当的重要，因此我们在做新托福阅读的题目的同时，也应该在空余的时候多阅读课外读物，原版杂志。譬如，国家地理，自然，今日美国等一些著名的原版杂志，这不仅可以扩充我们的背景知识，同时也可以补充我们在词汇量上的不足。 4. 在复习的最后阶段，做做模拟练习题是必不可少的。如果有条件的话，最好做一下模考软件。因为这样可以模仿新托福机考的真实场景。比较推荐的模考软件有Barron, Kaplan以及一些比较权威的模考网站。当然在你报名时托福官方网站提供给你的那一套不完整的模
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实用文档系列 文档编号：YL-SY-37339
考题也是很有参考价值的。
托福阅读TPO29第2篇:Competition
【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
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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 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.
【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
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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. 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 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
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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. 托福阅读TPO29试题第2篇:Competition
1.The phrase mechanisms of natural selection in the passage(paragraph 1)is closest in meaning to A.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?
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托福阅读复习的四个建议
