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题库 / OG2016-RC-110
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.
According to the passage, each of the following is true of endangered amphibian species EXCEPT:
They are among the rarest kinds of amphibians.
They generally have populations that are small in size.
They are in constant danger of extinction.
Those with decreasing populations are the most likely candidates for immediate extinction.
They are in danger of extinction due to events that sometimes have nothing to do with human activities.
题目分析：
文章细节题：濒临灭绝的两栖动物是：（除了）
选项分析：
A选项：他们是最稀少的物种。
B选项：他们数量很少。
C选项：他们在持续的濒临灭绝的危险中。
D选项：正确。数量正在下降的是最有可能立刻灭绝的：原文没提。
E选项：他们濒临灭绝可能是由于一些和人类活动无关的原因。
A选项：They are among the 【rarest】 kinds of amphibians.他们是最稀少的物种。
D选项：Those with decreasing populations are the 【most likely】 candidates for immediate extinction.正确。数量正在下降的是最有可能立刻灭绝的：原文没提。
排除法：
An endangered population is always rare(A), almost always small(B), and, by definition, under constant threat of extinction(C) even without a proximate cause in human activities(E).---->D
A&D选项都有最高级！虽然相较于原文A选项的“rarest”太绝对，但D提都没提更错
细节题。这里不要理解错了。这里相当于是已经认定了这种两栖生物已经是 endanger了，相当于要求我们找不满足 endangered 特征的条件。
已经认定endanger了，所以定位在endanger概念解释那一段，而不是第一段的数量减少这一段
A虽然太绝对但D更错
A他们确实很少，选错因为觉得rarest太绝对，但是有之一的话其实是可以接受的。
D文中没有说下降的就是最有可能灭绝的。
rc
EXCEPT题 注意；原文没提的选项，不要做多余假设
D选项：正确。数量正在下降的是最有可能立刻灭绝的：原文没提。
另：排除法
An endangered population is always rare(A), almost always small(B), and, by definition, under constant threat of extinction(C) even without a proximate cause in human activities(E).---->D
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.
第二段最后一句，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. 说 random factors可以导致物种灭绝，主要和population size相关，和size的改变趋势无关。---->D正好说反了
A declining population should not be confused with an endangered one
没有仔细读所有选项导致误选c
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仔细读文章，c错误，constant
An endangered population is always rare(A), almost always small(B), and, by definition, under constant threat of extinction(C) even without a proximate cause in human activities(E).---->D
错选E, 漏看了“not“ 非常傻的mistake。
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.
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
D选项定位在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.这句话的后半句。D说灭绝概率与数量变化趋势有关，而原文说的是独立于变化趋势，也就是无关
定位句： 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.
他们灭绝的可能性是取决于population size而不是取决于size的变化
C-定位原文第二段最后一句“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.” Population size 只是偶然因素导致灭绝；
D- sometimes have nothing to do with human activities. ---没看到sometimes就会容易误选；
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. 定位endangered，前面有两个不是，需要往后面找