Reading Comprehension
试题详情
文章：
| Line | While the most abundant and dominant species |
| within a particular ecosystem is often crucial in | |
| perpetuating the ecosystem, a “keystone” species, | |
| here defined as one whose effects are much larger | |
| (5) | than would be predicted from its abundance, can |
| also play a vital role. But because complex species | |
| interactions may be involved, identifying a keystone | |
| species by removing the species and observing | |
| changes in the ecosystem is problematic. It might | |
| (10) | seem that certain traits would clearly define a species |
| as a keystone species; for example, | |
| Pisaster ochraceus is often a keystone predator | |
| because it consumes and suppresses mussel | |
| populations, which in the absence of this starfish | |
| (15) | can be a dominant species. But such predation on a |
| dominant or potentially dominant species occurs in | |
| systems that do as well as in systems that do not | |
| have species that play keystone roles. Moreover, | |
| whereas P. ochraceus occupies an unambiguous | |
| (20) | keystone role on wave-exposed rocky headlands, |
| in more wave-sheltered habitats the impact of | |
| P. ochraceus predation is weak or nonexistent, | |
| and at certain sites sand burial is responsible for | |
| eliminating mussels. Keystone status appears to | |
| (25) | depend on context, whether of particular |
| geography or of such factors as community | |
| diversity (for example, a reduction in species | |
| diversity may thrust more of the remaining species | |
| into keystone roles) and length of species | |
| (30) | interaction (since newly arrived species in particular |
| may dramatically affect ecosystems). |
题目：
Which of the following hypothetical experiments most clearly exemplifies the method of identifying species’ roles that the author considers problematic?
选项:
A、A population of seals in an Arctic habitat is counted in order to determine whether it is the dominant species in that ecosystem.
B、A species of fish that is a keystone species in one marine ecosystem is introduced into another marine ecosystem to see whether the species will come to occupy a keystone role.
C、In order to determine whether a species of monkey is a keystone species within a particular ecosystem, the monkeys are removed from that ecosystem and the ecosystem is then studied.
D、Different mountain ecosystems are compared to determine how geography affects a particular species’ ability to dominate its ecosystem.
E、In a grassland experiencing a changing climate, patterns of species extinction are traced in order to evaluate the effect of climate changes on keystone species in that grassland.
答案:
C
提问：
老师， 我这种Application类型和这篇文章下一题都就是evaluation的类型， 总是出错 ，是什么原因？ 怎么提升呢？ 另外这道题我在c和d 纠结 ，选 D项是因为我觉得是因为最后一句话说了particular geography什么的
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