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OG20官方指南,建议同学们刷3遍。第一遍做题了解题型和考点,第二遍精刷,第三遍集中解决疑难问题。建议考生第一遍刷题采用官方正版纸质书籍,若遇到疑难问题,欢迎在此专区查阅解析,提供解析,参与题目讨论,与所有考生一起解决疑难问题。
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There are recent reports of apparently drastic declines in amphibian populations and of extinctions of a number of the world’s endangered amphibian species. These declines, if real, may be signs of a general trend toward extinction, and many environmentalists have claimed that immediate environmental action is necessary to remedy this “amphibian crisis,” which, in their view, is an indicator of general and catastrophic environmental degradation due to human activity.

To evaluate these claims, it is useful to make a preliminary distinction that is far too often ignored. A declining population should not be confused with an endangered one. An endangered population is always rare, almost always small, and, by definition, under constant threat of extinction even without a proximate cause in human activities. Its disappearance, however unfortunate, should come as no great surprise. Moreover, chance events—which may indicate nothing about the direction of trends in population size—may lead to its extinction. The probability of extinction due to such random factors depends on the population size and is independent of the prevailing direction of change in that size.

For biologists, population declines are potentially more worrisome than extinctions. Persistent declines, especially in large populations, indicate a changed ecological context. Even here, distinctions must again be made among declines that are only apparent (in the sense that they are part of habitual cycles or of normal fluctuations), declines that take a population to some lower but still acceptable level, and those that threaten extinction (e.g., by taking the number of individuals below the minimum viable population). Anecdotal reports of population decreases cannot distinguish among these possibilities, and some amphibian populations have shown strong fluctuations in the past.

It is indisputably true that there is simply not enough long-term scientific data on amphibian populations to enable researchers to identify real declines in amphibian populations. Many fairly common amphibian species declared all but extinct after severe declines in the 1950s and 1960s have subsequently recovered, and so might the apparently declining populations that have generated the current appearance of an amphibian crisis. Unfortunately, longterm data will not soon be forthcoming, and postponing environmental action while we wait for it may doom species and whole ecosystems to extinction.

【OG20-P447-575题】

Which of the following best describes the function of the sentence in highlight lines ?

  • 分析A选项
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  • 分析B选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  • 分析C选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  • 分析D选项
    xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  • 分析E选项
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该题目由网友LlpmDr1n提供。更多GMAT题目请
暂无雷哥网文字解析
当前版本由 thinku 更新于2015-10-29 18:10:42 感谢由 thinku 对此题目的解答所做出的贡献。
一般细节题
定位:Anecdotal reports of population decreases cannot distinguish among these possibilities, and some amphibian populations have shown strong fluctuations in the past.
(A) To give an example of a particular kind of study(与原文不符)
(B) To cast doubt on an assertion made in the previous sentence(与原文不符)
(C) To raise an objection to a view presented in the first paragraph(相符定位,第一段的report是个anecdotal report,所以可能存在没搞清楚decline的类型)
(D) To provide support for a view presented in the first paragraph(与原文相反)
(E) To introduce an idea that will be countered in the following paragraph(与文章内容不符)

题目讨论 7条评论)

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  • 用户头像

    Mariposa爱学习

    这篇文章讨论的核心是:两栖动物数量显著下降是不是意味着环境退化?
    第二段:首先我们要区分数量下降与灭绝,这是两个不同的概念
    第三段:然后我们还得区分这个数量下降是不是在正常的波动范围(因为有很多报告其实都没有考虑这个问题,看到数量下降就在那说,啊,两栖动物是不是要灭绝了呀,是不是咱们的环境退化了呀?经常大惊小怪)
    所以这句话的作用就是在暗示:第一段生物学家看到的报告是这种大惊小怪的报告,他们作出的判断也是不正确的
    1 0 回复 2020-11-15 17:27:11
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    xxxxiao

    高亮句讨论了anecdotal reports 报道population 数量下降的方式不能帮助生物学家分辨这些decreases是否是正常波动,下降到可接受的范围,或是真的会有灭绝危险。意味着第一段提到的“数量下降的报道表明catastrophic crisis"或许是错误的。

    0 0 回复 2019-12-31 17:38:38
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    jydebbie

    第一段的report不是recent report 吗
    0 0 回复 2019-10-15 20:15:21
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    432442ba

    第一段的report是个anecdotal report?怎么看出来的?
    0 0 回复 2019-10-10 22:27:57
    • 评论用户头像

      jydebbie回复432442ba

      我也想问!我裂开了

      1 0 回复 2019-10-15 20:14:19

    • 评论用户头像

      Mariposa爱学习回复 432442ba

      这篇文章讨论的核心是:两栖动物数量显著下降是不是意味着环境退化?

      0 0 回复 2020-11-15 17:27:01

    • 评论用户头像

      Mariposa爱学习回复432442ba

      可以看下我的理解哦

      0 0 回复 2020-11-15 17:27:54

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    Gmatlulu

    文章框架
    0 0 回复 2017-11-05 20:29:33
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    见过夏天去非洲拍动物世界

    To cast doubt on an assertion made in the previous sentence这里的previous sentence就这么耿直地指它前面的句子么········
    0 2 回复 2016-12-30 13:30:52
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    感觉自己萌萌哒

    第三段整体要表述的:对于生物学家来说,population declines比  extinctions更令人忧心:但是这里对decline也要做好区分,并不是所有的decline都意味着灭绝的,因为之前amphibian的数量在过去也显示很大的浮动。 这一段整体是反驳第一段的假设的。而高亮部分就是证据。
    A To give an example of a particular kind of study
     这一段没有涉及到a particular kind of study
    B To cast doubt on an assertion made in the previous sentence
    原文相反,定位本身是证明前面的句子的,非质疑
    C To raise an objection to a view presented in the first paragraph
    符合题干
    D To provide support for a view presented in the first paragraph
    非support,原文相反 
    E To introduce an idea that will be countered in the following paragraph
    无涉及
    2 0 回复 2015-11-03 11:03:47
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