Which of the following best describes the function of last sentence of the passage?

题目信息

The dry mountain ranges of the Western United States contain rocks dating back 440 to 510 million years, Line to the Ordovician period, and teeming with evidence of tropical marine life.

This rock record provides clues about one of the most significant radiations (periods when existing life-forms gave rise to variations that would eventually) evolve into entirely new species) in the history of marine invertebrates. During this radiation the number of marine biological families increased greatly, and these families included species that would dominate the marine ecosystems of the area for the next 215 million years. Although the radiation spanned tens of millions of years, major changes in many species occurred during a geologically short time span within the radiation and, furthermore, appear to have occurred worldwide, suggesting that external events were major factors in the radiation. And, in fact, there is evidence of major ecological and geological changes during this period: the sea level dropped drastically and mountain ranges were formed, in this instance, rather than leading to large-scale extinctions, these kinds of environmental changes may have resulted in an enriched pattern of habitats and nutrients, which in turn gave rise to the Ordovician radiation, However, the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood

A:it points out that the events described in the passage may be atypical

B:it alludes to the fact that there is disagreement in the scientific community over the importance of the Ordovician radiation

C:it concludes that the evidence presented in the passage is insufficient to support the proposed hypothesis because it comes from a limited geographic area

D:it warns the reader against seeing a connection between the biological and geologic changes described in the passage

E:it alerts the reader that current knowledge cannot completely explain the relationship suggested by the evidence presented

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正确答案： E:it alerts the reader that current knowledge cannot completely explain the relationship suggested by the evidence presented

问最后一句话的功能。说环境和生命之间的关系现在还不清楚，我们来看选项。A 指出了文章描述的事件是不是典型的，没说是否是典型的，杀。B还说agreement，和那句话方向都是反着的，杀C because后半部分内容说的很扯，杀。D说警告读者不要看出两者之间的关系，杀，很搞笑的一个选项。E说提醒读者现有知识还不能解释文章提出的那个关系，和我读到的信息令人发指的对应，留着。

笔记