我search了，没有发现这道题的讨论，答案是C，但我不知道E为什么不正确，因为E很象是ETS喜欢的取非样子。我的电子版是无法转换成Word的PDF版，快考试了没时间再敲一遍，大家帮忙看看吧，谢谢了。急！

GWD-10-Q9:

Although exposure to asbestos is the primary cause of mesothelioma, a slow-developing cancer, researchers believe that infection by the SV40 virus is a contributing cause, since in the United States 60 percent of tissue samples from mesotheliomas, but none from healthy tissue, contain SV40. SV40 is a monkey virus; however, in 1960 some polio vaccine was contaminated with the virus. Researchers hypothesize that this vaccine was the source of the virus found in mesotheliomas decades later.

Which of the following, if true, most strongly supports the researchers’ hypothesis?

A. SV40 is widely used as a research tool in cancer laboratories.

B. Changes in the technique of manufacturing the vaccine now prevent contamination with SV40.

C. Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.

D. In a small percentage of cases of mesothelioma, there is no history of exposure to asbestos.

E. In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40.

万分感谢携隐姐姐，找到Word版了

这题是有争议的。我倾向于E。

你去置顶贴里搜一下吧，以前已经有很多讨论了。

我感觉这题是没有争议啊。E   

c 植说有， 不影响结论吧

這题前人沒有定论，答案选Ｅ，但我认为是Ｃ。

看看一些前人的讨论：

词题应选C。
        开始的时候我也选了E，后来自己仔细思考明白了，到坛子里一看，lawyer的思路与我不谋而合，信心大增。（嘿嘿，我比较迷信lawyer的逻辑造诣）

引用你的分析：

Although exposure to asbestos is the primary cause of mesothelioma, a slow-developing cancer, researchers believe that infection by the SV40 virus is a contributing cause, since in the United States 60 percent of tissue samples from mesotheliomas, but none from healthy tissue, contain SV40. SV40 is a monkey virus; however, in 1960 some polio vaccine was contaminated with the virus. Researchers hypothesize that this vaccine was the source of the virus found in mesotheliomas decades later.

原文两个结论：

1、SV40 virus is a contributing cause

2、vaccine was the source of the virus found in mesotheliomas decades later

不同意。请你仔细观察本题的结构和问题的提问方式，虽然你的论述并没有错误，但问题问的是要你选出支持researchers' hypothesis 的项，所以题目可以看作只有最后一句话才是结论。而前面的所有论述都为了证明最后一句话有道理的evidence,而这些evidence的得出是经过一番论述后得到的，其中心句，也就是evidence中的论点是你上面所述的第一个结论。所以这两个结论看似都是结论，可是是在不同层次的结论。

中间隐含的结论的逻辑关系是 “疫苗并不是导致癌症的原因，被污染了的含病毒的疫苗才是致癌的原因”

不同意。逻辑关系应该是：“没有感染SV40的疫苗并不是导致癌症的原因，被污染了的含病毒的疫苗才是致癌的原因”

C把原文原文的提亮部分重复了一遍，发现了1960年的疫苗里有病毒，仅仅说明了结论的一部分，缺乏最关键的结论：是疫苗自身产生了病毒，还是被污染后感染了病毒？没有指出致癌的真正的原因，被病毒污染的疫苗！

C并非只是简单的说明高亮部分，而是一个事实性的支持，请注意如下词语：recently discorvery, still, 说明被污染了的疫苗的确至今仍然具有感染性（通过研究事实证明）。

E，指出了这中间的逻辑关系，疫苗没有被感染，没有找到SV40，说明疫苗不是致癌的原因，没有被污染，就不会致癌！

E选项如同你说的没有错，但是请注意这只是在加强前面evidence的结论，而文章已经将evidence 的结论认为是定论了，而且也没有让你去加强，为无关选项。

请仔细看问题，仔细体会lawyer 的解释。