对费费38题A选项的不解，请指点

ssss

38. Amphibian populations are declining in numbers worldwide. Not coincidentally, the earth’s ozone layer has been continuously depleted throughout the last 50 years. Atmospheric ozone blocks UV-B, a type of ultraviolet radiation that is continuously produced by the sun, and which can damage genes. Because amphibians lack hair, hide, or feathers to shield them, they are particularly vulnerable to UV-B radiation. In addition, their gelatinous eggs lack the protection of leathery or hard shells. Thus, the primary cause of the declining amphibian population is the depletion of the ozone layer.
Each of the following, if true, would strengthen the argument EXCEPT:
(A) Of the various types of radiation blocked by atmospheric ozone, UV-B is the only type that can damage genes.
(B) Amphibian populations are declining far more rapidly than are the populations of nonamphibian species whose tissues and eggs have more natural protection from UV-B.
(C) Atmospheric ozone has been significantly depleted above all the areas of the world in which amphibian populations are declining.
(D) The natural habitat of amphibians has not become smaller over the past century.
(E) Amphibian populations have declined continuously for the last 50 years.

答案是A

但是我觉得BCDE都可以是support，但是A也可以理解成support，因为，此题的结论是“引起两栖动物种群减少的根本原因是因为臭氧层遭到破坏”，A说在臭氧层可以阻隔的各种射线中，UV-B是唯一一种可以破坏基因的。

臭氧没了－》UV-B到达地球（UV-B可以破坏基因）－》两栖动物种群减少－》臭氧层遭到破坏是两栖动物减少的根本原因

A给出了一个必要条件，应该也是support吧？

请大侠指点！

kathy72

根据A, 其给出的并不是得出原文结论的必要条件,而是 UV-B是 genes damage的必要条件, 而题目要求加强的结论是臭氧层遭到破坏是两栖动物减少的根本原因, 因此,基本上A是一个无关选项. 因为加强的方向应该是从臭氧层的作用与两栖动物增减之间的联系来论证的. 加强可以非充分, 非必要. 当然, 充分或必要也可以加强.

ssss

是不是应该这么理解：

A说在臭氧层可以阻隔的各种射线中，UV-B是唯一一种可以破坏基因的。

UV-B是不是唯一可以破坏基因的射线与本题无关？

kathy72

可以这么理解.

joe11

Another way to interprete the answer.

Assume A is not correct, then there are some other radiation will damage Amphibian's gene. Thefore, the depletion of ozone will create more UV-B and other radiations. And hence, the Amphibian population will decline faster. Hereafter, the decline of Amphibian population is still because of the depletion of ozone. It does not weaken the original conclusion. Therefore, A is not the answer. In this counter-deduction process, you can see whether UV-B is the only type of radiation, which can damage genes, is irrelevant to the original conclusion.

Proof that D is wrong:

Assume D is wrong. Then the shrink of Amphibian's habitat could lead to its population decline, which weaken the original conclusion. Therefore, D strengthen the conclusion and should not be the answer.

kevinwww

5楼的很牛呀！

我想了半天没想出来，看了5楼的才明白点。

A可以理解为不是加强，反倒是削弱结论！因为如果UV-B不是唯一可以破坏基因的射线，那么臭氧层的作用就会更大（不但阻止了UV-B还阻止了其他可以破坏基因的射线），所以有了唯一性，臭氧层的作用反倒给减小了！

tony6

新出的费费详解版此题的答案是D，并有为什么选D的解释，不会是笔误，请斑竹确认是否错误，我认为此题毫无疑问是A。

lawyer_1

旧版的费费该题答案为A。

1。D是错的：因为D提出一个amphibian population 减少的它因

2。原文推理：amphibian population 减少，同时臭氧层也减少，臭氧层能阻挡UV-B，UV-B会DAMAGE基因。所以（结论），臭氧层的减少是amphibian population 减少的原因。

3。A不是必要条件。将A取非后，在臭氧层阻挡的射线中，UV-B不是唯一一种能DAMAGE基因的。也就是还有其他也能DANANGE基因。其他射线也能DAMAGE基因这个结果并不能使结论不成立。同时A（UV-B是唯一能DAMAGE基因的）也没有通过加强证据或排除它因等形式加强结论。

4。其他选项都是通过证明证据或排除它因的方式支持结论。

tony6

谢谢LAWYER

ricky663

反正D肯定不是正确答案，是一个它因，所以也就A可能了