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题库 / Prep2007E2-CR-24
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?
SV40 is widely used as a research tool in cancer laboratories.
Changes in the technique of manufacturing the vaccine now prevent contamination with SV40.
Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.
In a small percentage of cases of mesothelioma, there is no history of exposure to asbestos.
In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40.
说明了A→B的联系
P 疫苗被病毒污染
C 疫苗就是病毒/疾病来源
重点在于，谁才是病毒/疾病的来源
A 病毒被广泛使用，那导致疾病的病毒来源是谁呢？不知道，不要脑补
B 现在可以防止污染，现在 无关
C still show traces of the virus.疫苗中仍然有病毒的痕迹 残留，
原文前提已经说了 however, in 1960 some polio vaccine was contaminated with the virus.病毒被感染了，
重复前提，没用，不能加强前提
D 无关，提到的是第一句背景里面的信息，肯定和结论无关，这里说的是contributing cause
c只是单纯说了疫苗里有病毒，但是并不能说meso是因为疫苗被污染，然后有sv40导致的
需要找一个能加强P和C推理的选项。
例如：P 去年发洪水把房屋冲塌了 C 不是房屋质量的问题
加强项应该是说明房屋质量好。如果选项说去年确实发了洪水（重复文章中事实），对于说明C没有实质的加强效果
tissue不是纸巾是组织啦23333。还有我是这样想的：C 就算现在还能从那批疫苗中trace到virus，也不代表当年得M病的人是那批vaccine害的（some这个词很重要），也许他们接触了其他virus来源。而E是很好的无因无果的支持（never一词也很重要）。登录 或 注册 后可以参加讨论
E里没有感染的疫苗就不含SV40,说明疫苗本身不含SV40，正文中含SV40的疫苗是被感染过的登录 或 注册 后可以参加讨论