passage 15 在岛屿上研究进化

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文章讲解：

①Ecologists study how millions of species share the world, rather than take on the whole planet at once; they generally focus on a single ecosystem, be it a prairie, a tidal flat[剑1] ,or a sanddune . [剑3]  ②Even within those limits, they are frustrated by porous frontiers. ③As a result, ecologists have done some of their most important work on islands, nature’s own isolated laboratories, which may be colonized only a few times over the course of millions of years.[剑5] ④On them, ecologists have figured out how the size of a given habitat determine how many species it can support. ⑤They have then applied that knowledge to the mainland, showing how fragmented ecosystems become like archipelagoes[剑7] ,where extinctions can strike. 

①事实

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② 事实/生态学家自己的观点

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③

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④

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⑤

 [剑1]潮汐平原

 [剑7]͵ɑrkəˋpɛlə͵go群岛

1. It can be inferred that the term “porous frontiers” is used to refer to

单词题变体

A. a tendency for the area of an ecosystem to shrink 没有证据

B. human-caused processes that alter the character of an ecosystem 没有证据

C. movement of species into an ecosystem from outside 符合

D. variation in what theterm “ecosystem” signifies 没有证据

E. lack of protection for endangered habitats 没有证据

 

2. In the context in which itappears, “isolated” most nearly means

A. completely uncontaminated

B. somewhat unusual

C. extremely rare

D. relatively inaccessible 符合

E. strictly confined