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 particlularly 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 ture, would strengthen the argument EXCEPT: (A) Of the various types of radiation blocked by atmosphiric 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 bcome smaller over the past century. (E) Amphibian populations have declined continuoulsy for the last 50 years. 这题的正确答案为何是A而不是D呢？
以下是引用oktostart在2004-1-31 11:00:00的发言： and which particlularly vulnerable to UV-B radiati这个which指什么啊 谢谢
对不起，原题有一句关键话忘了敲了，现补充如下，祥见黑体字部分： 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 ture, would strengthen the argument EXCEPT: (A) Of the various types of radiation blocked by atmosphiric 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 bcome smaller over the past century. (E) Amphibian populations have declined continuoulsy for the last 50 years.
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发表于 2004-1-30 23:12:00
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