继续讨论，C还是E

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. 答案:E

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

1. SV40 is widely used as a research tool in cancer laboratories.
2. Changes in the technique of manufacturing the vaccine now prevent contamination with SV40.
3. Recently discovered samples of the vaccine dating from 1960 still show traced of the virus.
           
4. In a small percentage of cases of mesothelioma, there is no history of exposure to asbestos.
5. In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40.

  我选E，原来也选C，思维发生了巨变，如下

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

我们要加强的是reseacher的hypothesis

题干中出现了两次researcher，一次是  researchers believe that ，一次是最后一句话  Researchers hypothesize that

我们现在要加强的是最后一句话，please focus 在最后一句话

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.

1960年的疫苗就是今天在癌症找到的virus的源头，source

C的错误有两条，第一，以偏概全，只是集中在最后一句话，没有照顾到整个推理链

              第二，Recently discovered samples of the vaccine dating from 1960 still show traced of the virus. 最近发现的疫苗的样品，来源于1960年的那批疫苗，仍然可以找到virus的踪迹，我猜1960年的那批疫苗被冷冻起来，所以多年后仍然没有失效，但是这只是对原文的一个简单的重复。因为conclusion里只说vaccine是源头，并没有说现在有没有效，设想一下，我们现在还会注射1960年的冷冻疫苗吗，不会，应该是当时这种virus在人体内存在后，在人体内不断演化传代，到近期才表现出来症状，因为1960年的那批疫苗导致了那个病毒从猴传到了人，关于那个病毒在疫苗中的状态，我们就不关心了。

E 结合了整个推理链给出了答案，就是说在疫苗没有被感染过的国家里，癌症病人里没有发现sv病毒，多好的说明，建立起sv和疫苗之间的关系。

这个题关键是要理解source，source不是说 我们今天注射了1960年的疫苗，而是说那是起源，至于这么多年这个virus怎么在人体内演变传代，我们就不管了.