GWD TN-22-Q5

门萨来了

Q5. Which of the following can be inferred from the passage regarding the geologic changes that occurred during Ordovician period?

A.      They were more drastic than those associated with other radiations

B.       They may have created conditions favorable to the evolution of many new life-forms

C.      They may have caused the extinction of many of the marine species living in shallow waters

D.      They may have been a factor in the development of new species adapted to living both on land and in water

E.       They hastened the formation of the extensive dry regions found in the western united states

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The dry mountain ranges of the western United States contain rocks dating back 440 to 510 million years, 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 pattem 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

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此题目答案为E

但是B为什么不对呢?

 

UMLwang

Both choices make sense. I prefer E since it is a relatively certain one compared to B.  In addition, from the last sentence in the passage, we know the relation is not fully understood....

门萨来了

好象是这么个道理......

谢谢!

fabiozhu

1楼说的好！！

crystalbain

不同意，E选项是以肯定的语气说的，而文中没有任何一个地方可以看出当时的那个地质变化对现在这个地方时dry mountain region有任何contribution。而B选项用的是不确定的语气，且表达的意思是文中透露出的---那种地址变化没有造成大规模的物种灭绝，而提供了更多的生存环境种类和供生物生存的营养。