feifei逻辑好难！求助！

各位xdjm，

我昨天做了一套feifei test2，竟然超时5分钟，且18道题中错了7题！！临考不到20天了，急！

请教各位，狒狒的题比考试难吗？还是差不多？

考试不到20天了，还做FEIFEI没必要了吧。应该练GWD。个人意见。也是以前NN的经验之谈。

听说feifei是很好的逻辑联系材料，不做完觉得心里不踏实。

刚才又做了一套，没有超时，错了3个！波动太大了吧！

有一题不理解，还望指教：

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D，但本人认为应该是A。对A取非，即如果臭氧层里还有其他物质对genes有破坏作用，那么臭氧层的减少对amphibian的破坏作用更大，从而并没有削弱原题中的结论，因此A并没有增强结论作用。

D中说明amphibian的自然生存领地并没有减少，是排除了可能导致amphibian减少的其他原因。因此对原题中的结论有增强的作用。

大家说怎么理解呢？

答案a支持作用，答案d是唯一无关选项。

我这样理解，

结论：两栖类动物数量减少的原因是臭氧层的减少。

其中一个前提是两歧类动物最易受 UV-B radiation的伤害

A．在各种被臭氧层阻碍的辐射中 UV-B是唯一可伤害基因的一种。

支持了文中所说“因为臭氧层减少UV-B伤害两栖动物并使其减少的结论”

D．栖息地与两栖类动物的个数无关。

但本人还是认为没有必要说明臭氧层阻碍的辐射中UV-B是唯一的，如果还有其他对基因有害的物质也被臭氧层阻碍的话，也不影响结论的成立。

而栖息地的减少当然会影响两栖类动物的个数了，当他们连生存的地方都没有了，怎么还能存活呢？

我的这个理解难道不对吗？还是我钻牛角尖了？