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题库 / OG2016-RC-107
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.
The primary purpose of the passage is to
assess the validity of a certain view
distinguish between two phenomena
identify the causes of a problem
describe a disturbing trend
allay concern about a particular phenomenon
文章大意：
1. 近期报道：两栖动物（amphibian）的额数量在下降
所以环境学家认为（claim）：要对此采取行动 & 这是人类活动导致环境恶化的信号
2. 这个claim对不对呢？敲黑板：要区分“正在减少的数量（declining population）”和“濒临灭绝的数量（endangered population）”
3. 数量下降比灭绝更糟糕。但也要区分“表面的下降”、“可接受的数量减少”、“导致灭绝的下降”
4. 虽然目前的两栖动物数量下降的严重程度存疑，但如果我们马后炮，后果也很严重。
题目分析：
文章主旨题
选项分析：
A选项：正确。评估一个理论的有效性：文章第一段的学者提出：目前两栖动物的数量下降是灭绝的信号，我们要采取行动。后文开始评估这个claim，真的是灭绝的信号吗？
B选项：区分两个现象：文章只提到了一个现象——两栖动物的数量下降。
C选项：辨别一个问题产生的原因：problem指的是两栖动物数量下降，但文章并没有提到数量下降的原因。
D选项：描述一个令人不安的趋势：文章确实提到了一个趋势：两栖动物数量下降，但全文的重点是它的背后意义到底是不是像学者claim的那样。
E选项：减轻关于一个现象的忧虑：文章没有出现“减轻忧虑”。
有人说a要灭绝了，但是到底是濒危还是灭绝呢？这二者可是不一样的哦。
就算我们知道二者不一样，我们还是没有好办法来辨认。
allay减轻缓和
1. 近期报道：两栖动物（amphibian）的额数量在下降
所以环境学家认为（claim）：要对此采取行动 & 这是人类活动导致环境恶化的信号
2. 这个claim对不对呢？敲黑板：要区分“正在减少的数量（declining population）”和“濒临灭绝的数量（endangered population）”
3. 数量下降比灭绝更糟糕。但也要区分“表面的下降”、“可接受的数量减少”、“导致灭绝的下降”
4. 虽然目前的两栖动物数量下降的严重程度存疑，但如果我们马后炮，后果也很严重。
文章结构：
may be 【signs】 of a general trend toward extinction, and ...... "amphibian crisis," which, in their view, is an 【indicator】 of general and catastrophic environmental degradation due to human activity
现象-claim->evaluate claim-> declining one and endangered one---evaluate amphibian populations -> attitude: postponing environmental action while we wait for it may doom species and whole ecosystems to extinction.
重点在第二段的开头：To evaluate these claims--就是选项“assess the validity of a certain view”
A选项：正确。评估一个理论的有效性：文章第一段的学者提出：目前两栖动物的数量下降是灭绝的信号，我们要采取行动。后文开始评估这个claim，真的是灭绝的信号吗？
C选项：辨别一个问题产生的原因：problem指的是两栖动物数量下降，但文章并没有提到数量下降的原因。（注意关键词“sign”"indicator", 只是相关性的信号，不是因果！！）
E选项：[allay] concern about a particular phenomenon [减轻]关于一个现象的忧虑：文章没有出现“减轻忧虑”。
allay 减缓
rc
文章结构：
现象-claim->evaluate claim-> declining one and endangered one---evaluate amphibian populations -> attitude: postponing environmental action while we wait for it may doom species and whole ecosystems to extinction.
重点也在开头：To evaluate these claims--就是选项“assess the validity of a certain view”
第三段长难句分析： Even here, ～ declines and threaten declines. 生态变化可以造成两种decline，一种是可以造成数量在可接受范围内降低，一种是会降低到可以接受的底线之下。
主题是evaluate these claims
paragraph 1: declines in amphibian populations may constitute a crisis, one that indicates humans' catastrophic effects on the environment.
paragraph 2: whether claims of crisis-level extinctions as a result of human activity are valid. discuss the possible causes of extinctions
paragraph 3: biologists' prioritization of population declines over extinctions
paragraph4; the fact that we lack extensive long-term data on amphibian populations.
第一段提出观点——两栖动物的decline标志着extinction
第二段评估该观点，主要是反对，引入decline和endangered population的definition，认为二者不同，前者和趋势相关，后者和population size的绝对数值相关，后者才确定会导致extinction
第三段详述decline，认为decline表明ecological context的变化，根据population size的多寡，decline本身也分为三种类型，而现有报道太业余，很难辨别两栖动物的decline的类型，只知两栖动物的population size波动很大
第四段，上述的无法辨别是因为long-term数据不足导致的，借着用实例解释波动——以为要灭绝的，又多起来，多起来的，现在又crisis了，size很不稳定。最后说long-term数据不足的事很难得到解决，可能到最后两栖动物都灭绝了也无法解决
all but=几乎 about
To evaluate these claims, it is useful to make a preliminary distinction that is far too often ignored ==
assess the validity of a certain view
两栖动物的灭绝的拯救取决于人类对于环境的立即行动，因为人类活动是这场大浩劫的主因。第二段就此评价，动物数量的下降与动物的灭绝对比；第三段动物学家更担心数量的下降，原因。所以选A
这篇又是6对4 怎么稍微难点就全对不了 而且6道题用了9分伴
错选B。要分析作者区别两种现象distinction and population decline是在做什么。作者实际是在evaluate the claims 也就是 assess the validity of certain view.
To evaluate these claims, it is useful to make a preliminary distinction that is far too often ignored.
第一段提出一个观点：amphibian要灭绝了，是因为人类对环境的破坏
后面几段从不同角度评估了这个观点
P2第一句给了明确的提示，To evaluate these claims 误选C，并不是主要探讨造成数量和种类下降的原因。
整篇都在评价环境学家的claim：两栖动物灭绝是因为人