LR9306-2-11

sevfye

A distemper virus has caused two-thirds of the seal population in the North Sea to die since May 1988. The explanation for the death cannot rest here, however. There must be a reason the normally latent virus could prevail so suddenly: clearly the severe pollution of the North Sea waters must have weakened the immune system of the seals so that they could no longer withstand the virus.

Which one of the following, if true, most strongly supports the explanation given in the argument?
A. At various times during the last ten years, several species of shellfish and seabirds in the North Sea have experienced unprecedented  steep drops in population.

B.By reducing pollution at its source, Northen Europe and Scandinavia have been taking the lead in preventing pollution from reaching the waters of the North Sea

C.For many years, fish for human consumption have been taken from the waters of the North Sea.

D.There are two species of seal found throughout the North Sea area, the common seal and the gray seal.

E. The distemper caused by the virus was a disease that was new to the population of North Sea seals in May 1988, and so the seals' immune systems were unprepared to counter it.

A,我是用排出法选Ａ的．但是，正着看，Ａ中也没支持就是pollution的原因．提到shellfish and seabirds的作用是什么？

crusoecrusoe

事实为：疾病爆发—》海豹死亡。

逻辑链：污染—》海豹免疫力下降，免疫力下降—》抵抗不了病毒侵害，病毒侵害—》疾病爆发—》海豹死亡。即污染—》海豹死亡

A答案，“shellfish and seabirds”的急剧减少作为explanation，只要作为论据（explanation）支持以上逻辑链中的任何一个推论,便起到support的作用。（可以说shellfish and seabirds，与海豹共同生活在一个环境下，它们种群的急剧减少，虽然原因不明，但也算是一种若隐若现的支撑，至少在减少趋势上是一致的）

如果有更好的解释，欢迎赐教。

 

白骨妖精

我是把这个argument套用到logic的frame work里面：

Which one of the following, if true, most strongly supports the explanation given in the argument?

The explanation is "the severe pollution of the North Sea waters must have weakened the immune system of the seals so that they could no longer withstand the virus"

（这里称为explanation，但这个statement在这个argument里充当的是conclusion的角色）

选项A，可以看成是对"the pollution of the North Sea"的一种证实，尽管这个证实不是100%的（i.e. the question used "support", not "justify")。

实际上这个选项addressed an assumption/logic gap：

Premise 1：A distemper virus has caused two-thirds of the seal population in the North Sea to die since May 1988

Premise 2: the normally latent virus could prevail so suddenly

Conclusion: the severe pollution of the North Sea waters must have weakened the immune system of the seals so that they could no longer withstand the virus

Missing Premise/Assumption: there has been an increase in the severity of the pollution in North Sea lately