1. GWD32—32-34 奥陶纪海洋生物进化
Ordovician marine life evolutionThe 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 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. radiation.适应性进化
第一句提出西部干旱山脉充分提供了奥陶纪热带海洋生物的证据。这些石头提供了海洋无脊椎动物史上最重要的适应性进化线索。这段期间，海洋生物大量增加，这些新进化的种族统治了以后215m年的海洋生态系统。尽管这段进化期跨越了1千万年，重大物种进化是在此期间很短时间内发生的，而且是全球性的，说明外在事件是最大影响因素。而且有证据证明：海平面大幅下降，山脉形成，这样，不仅没有大规模物种灭绝，反而丰富了栖息环境和饮食营养，反过来促进了奥陶纪生物进化。尽管如此，这些生态环境因素和物种的多样性的关系还没被完全了解。
文章讨论中心是：奥陶纪
海洋生物
的进化， 主题是：推测是由环境因素导致进化
答案应该是BBE，大家讨论一致同意，没有问题
Q4: The passage is primarily concerned with A. evaluating the evidence of a major geologic period and determining its duration B. describing an evolutionary phenomenon and speculating about its cause
正确 suggesting that external events were major factors in the radiation. C. explaining the mechanisms through which marine life-forms evolved during a particular period D. analyzing the impact on later life-forms of an important evolutionary development E. contrasting a period of evolutionary change with other such periods --------------------------------------------------------------- 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 正确，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. 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 海洋两栖动物没有提到，只说了海洋无脊椎动物和海洋生物 E. They hastened the formation of the extensive dry regions found in the western united states 更本没有提到，原文只说了美国西部的Dry Mountain ---------------------------------------------------------------- Q6. Which of the following best describes the function of last sentence of the passage ? 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 geolgic changes described in the passage E. it alerts the reader that current knowledge cannot completely explain the relationship suggested by the evidence presented in the passage
正确 | 
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发表于 2008-8-11 02:46:00
