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标题: prep2-24! [打印本页]

作者: alpaca 时间: 2010-8-23 21:03
标题: prep2-24!

24.(28903-!-item-!-188;#058&004064)

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.

(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.

我能理解E是正确的，可是不知道为设么C是错误的……
求NN给解释一下吧~~~~谢谢啦！
PS:我只搜到了一个帖子，而且也没有看明白……

作者: 2008115061 时间: 2010-8-23 21:36
这道题LZ要好好看清作者argue的是什么。.Researchers hypothesize that this vaccine was the source of the virus found in mesotheliomas decades later.

1. C选项证实了前半段：病毒在疫苗里。但是后一段，病毒在meso里面就得不到验证了。E能弥补这点。

2.文章说的是在过去的情况，并没有说现在怎样。拿现在的数据说明不了什么问题

希望能有帮助~

作者: gaor 时间: 2010-8-23 22:15
文章：‘exposure to asbestos‘ 是引起m癌症的原因，研究又认为SV40也是起因之一，因为60%的m癌症tissue含有SV40。
1960年的一些被污染的polio vaccine中含有SV40。所以研究者认为现在癌症中发现的SV40来自于那时候的polio vaccine。

问题：支持' this vaccine was the source of the virus found in mesotheliomas decades later'的选项

E是正确的：如果polio vaccine没有被污染，m癌症tissue找不到SV40，

C实际上是一个文中的已知条件，那些被污染的polio vaccine中有SV40，对结论没有额外帮助。

作者: alpaca 时间: 2010-8-23 23:35
谢谢2楼NN!
祝过两天考出好成绩！^^

作者: alpaca 时间: 2010-8-23 23:38
开朗了~~~谢谢3楼！

作者: 199249712 时间: 2012-4-28 13:09
感觉这个题的问题就是看谁是结论吧。。。既然PP已经确定答案是E 那么就默认了最后一句话是结论。。。

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