GWD-10-Q9 求助...

jojochen310

amumu 发表于 2009-8-30 20:04
我觉得E还是有个问题：如果vaccine中没有SV40，结果m的样本中也没有，岂不是也说明SV40也不是m的致病原因之 ...

而且E这种答案往往错的有木有阿...选C的中枪...

emiliejiang

Moonpainter 发表于 2009-8-24 17:26
GWD-10-Q9Although exposure to asbestos is the primary cause of mesothelioma, a slow-developing cance ...

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;（前面这么多都是背景：A是M的主要原因，同时SV40也是原因之一。） 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.
(题目问的hypothesis也就是论证的结论，即疫苗是为M病带来SV40的罪魁祸首。所以逻辑如下：vaccine→SV40→M ；SV40和M的关系是确定的，论证的内容是vaccine是唯一能导致SV40的因素,也就是SV40(a contributing cause of SV40→ M)→vaccine)
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.（非vaccine→非SV40）

emiliejiang

angela7258 发表于 2010-11-8 23:17
我觉得E还是有个问题：如果vaccine中没有SV40，结果m的样本中也没有，岂不是也说明SV40也不是m的致病原 ...

已经说了，只有百分之60的人是因SV40致病，没有SV40说明是exposure to a 致病或者其它因素致病

emiliejiang

sdcar2010 发表于 2010-11-8 23:54
The way I looked at the problem is the following:1) Read the question stem: Which of the following,  ...

“Both (D) and (E) look interesting.  However the phrase "a small percentage" in answer (D) bothers me. Even if (D) is right, it could only support "a small percentage" of the argument.  ”
I choose D， but now I understand why it's incorrect: in the statement of the causes, we only say EXPOSURT TO A and SV40 are two possibilities, but we do not say they are the only two. Therefore, "a small percentage"could be other things, neither EXPOSURE nor SV40.