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原文： There are recent reports of apparently drastic declines in amphibian populations andof extinctions of a number of the world’s endangered amphibian species. Thesedeclines, if real, may be signs of a general trend toward extinction, and manyenvironmentalists have claimed that immediate environmental action is necessaryto remedy this “amphibian crisis,” which, in their view, is an indicator ofgeneral and catastrophic environmental degradation due to human activity.
To evaluate these claims, it is useful to make a preliminary distinction that isfar too often ignored. A declining population should not be confused with anendangered one. An endangered population is always rare, almost always small,and, by definition, under constant threat of extinction even without aproximate cause in human activities. Its disappearance, however unfortunate,should come as no great surprise. Moreover, chance events—which may indicatenothing about the direction of trends in population size—may lead to itsextinction. The probability of extinction due to such random factors depends onthe population size and is independent of the prevailing direction of change inthat size.
For biologists, population declines are potentially more worrisome than extinctions. Persistent declines, especially in large populations, indicate achanged ecological context. Even here, distinctions must again be made amongdeclines that are only apparent (in the sense that they are part of habitualcycles or of normal fluctuations), declines that take a population to somelower but still acceptable level, and those that threaten extinction (e.g., bytaking 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 isindisputably true that there is simply not enough long-term scientific data onamphibian populations to enable researchers to identify real declines inamphibian populations. Many fairly common amphibian species declared all butextinct after severe declines in the 1950s and 1960s have subsequentlyrecovered, and so might the apparently declining populations that havegenerated the current appearance of an amphibian crisis. Unfortunately, long-term data will not soon be forthcoming, and postponing environmental actionwhile we wait for it may doom species and whole ecosystems to extinction.
问题: Itcan be inferred from the passage that the author believes which of thefollowing to be true of the environmentalists mentioned in lines 5–6(标黄部分）? (A)They have wrongly chosen to focus on anecdotal reports rather than on thelong-term data that are currently available concerning amphibians. (B)Their recommendations are flawed because their research focuses too narrowly ona single category of animal species. (C)Their certainty that population declines in general are caused by environmentaldegradation is not warranted. (D)They have drawn premature conclusions concerning a crisis in amphibianpopulations from recent reports of declines. (E) Theyhave overestimated the effects of chance events on trends in amphibianpopulations.
正确答案是D，我选的C。 D我想了一下，如果从文章作者的整体结构来把握的话能想明白，第一段提出了environmentalists认为可能是人类活动造成degradation从而造成动物人口数量下降这么一个观点。然后第三段又表示人口数量波动时有常事不足以判断是否是真正的结论，因为scientific data还不足够long term来判断人口数量波动，所以科学家为之过早。
但是C我感觉也没有错啊，"科学家确信人口数量下降是由degradation导致这一说法不令人信服"。整个文章作者的也是在评价这一观点的真实性,作者也说了evaluate这些claim。然后OG的解释是文中没有任何地方说科学家他们确信什么东西，但是我觉得解释的有点牵强，因为本来原文中就说"in their view, is an indicator blah blah",既然都是观点了那还不是确信吗？ 我感觉og的解释无法令人信服....
有没有大神能够指点一下，谢谢谢谢！
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发表于 2017-4-25 23:03:47
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