Q4~Q6: GWD32—32-34
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 providesclues about one of the most significant radiations (periods when existing life-forms gave riseto variations that would eventually evolve into entirely new species) in thehistory of marine invertebrates. During this radiation the number of marinebiological families increased greatly, and these families included species thatwould 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 manyspecies occurred during a geologically short time span within the radiationand, furthermore, appear to have occurred worldwide, suggesting that externalevents were major factors in the radiation. And, in fact, there is evidence of majorecological and geological changesduring this period: the sea level dropped drastically and mountain ranges wereformed, in this instance, rather than leading to large-scale extinctions, thesekinds of environmental changes may have resulted in an enriched pattern of habitats and nutrients, which in turn gave rise tothe Ordovician radiation. However, the actual relationship betweenthese environmental factors and the diversification of life forms is not yetfully understood.
Q5. Which of the following can be inferredfrom the passage regarding the geologic changes that occurred during Ordovicianperiod?
A. They were more drastic than those associatedwith other radiations
B. They may have created conditionsfavorable to the evolution of many newlife-forms
C. They may have caused the extinction of manyof the marine species living in shallow waters
D. They may have been a factor in thedevelopment of new species adapted to living both on land and in water E. They hastenedthe formation of the extensive dry regions found in the westernunited states
大家覺得答案是B or E ?
我是覺得B好像比較好@@"作者: laurawang2234 时间: 2011-2-24 06:44
B选项created conditionsfavorable to the evolution of many newlife-forms ，感觉联想太多了作者: tingting520 时间: 2011-2-25 06:48
这道题我也选B了，
thesekinds of environmental changes may have resulted in an enriched pattern of habitats and nutrients, which in turn gave rise tothe Ordovician radiations 【radiations (periods when existing life-forms gave riseto variations that would eventually evolve into entirely new species) 】
所以推得了B。。。
请问怎么解释E呢？作者: queenie924 时间: 2011-2-27 08:58
阅读题的答案一定是原文显明而不是我们推导出来的。选择2就是典型的推理。
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