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 traced 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.作者: 我系大P 时间: 2011-6-6 04:39
这题是争论题, 我贴上当时的争论和我自己的看法(最后的红色字). lz再仔细体会体会吧. 不过老实说, B肯定不对, 因为是无关, now prevent和原文没有关系. 下面的论述都出自CD的资料. 这题的答案最后是C.
镯子MM，受了你不少恩惠，无以为报。今天瞅见这题，想详细给你讲讲，聊表心意。 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： Althoughexposure to asbestos is the primary cause of mesothelioma, a slow-developingcancer, researchers believe that infection by the SV40virus is a contributing cause, since in the United States 60 percent of tissuesamples from mesotheliomas, but none from healthy tissue, contain SV40. SV40 isa monkey virus; however, in 1960 some poliovaccine was contaminated with the virus. Researchers hypothesize thatthis vaccine was the source of the virus foundin mesotheliomas decades later. 原文两个结论： 1、SV40virus is a contributing cause 2、vaccinewas 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。 这题我是选C. 我没有想太复杂. Support的方式是对原文的论述做肯定. E现在看来也好像有道理. 但是不选的原因是提到Finland好像会出现无关. 再体会之后, 明白了这一点. E的论述本身没有错误. 但是E提出的观点对科学家的假设没有帮助. E的意思只是说没污染的疫苗就没有SV40, so? 这个东东没什么用. 相反,C说那个病毒随时间推移还是一直存在. 而文中的观点是病毒是导致cancer的原因. 由于没有消失, 所以至今还是那个原因导致. 所以是C作者: sdcar2010 时间: 2011-6-6 08:30
E supports the conclusion since it confirms: No contamination of the polio vaccine --> No SV40 in mesotheliomas. A contrapositive of the this logic chain is : SV40 in mesotheliomas --> contamination of the polio vaccine. Converted into the GMAT language: contamination of the polio vaccine is necessary (source) for SV40 to be found in mesotheliomas.作者: sdcar2010 时间: 2011-6-6 08:41
C. Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.
The problems with this choice: 1) Do you know when was the virus introduced into the vaccine? No. Not sure. Could it be after 1960? Yes, it is possible. 2) Does this further support the notion that the virus found in vaccine was the virus found in mesotheliomas? No. It only confirms the finding that virus WAS found in the vaccine.作者: sdcar2010 时间: 2011-6-6 08:44
In other words, if you insert C directly into the stimulus before the conclusion, there is no significant change in the likeliness of the old hypothesis. Thus, choice C) is not as strong as E) to help reach the conclusion of the argument.作者: sinrever 时间: 2011-6-12 22:38
Thanks sdcar DN!作者: sinrever 时间: 2011-6-12 22:38
Thanks sdcar DN!作者: lala974 时间: 2011-7-13 02:00
thx作者: carbonzju 时间: 2011-10-6 11:39
prep题目啊， 选E