GWD-10-9

billgong

haibinyouli, 你和我的观点一模一样。

见 http://forum.chasedream.com/dispbbs.asp?BoardID=24&ID=78495&replyID=824090&skin=1

古镯

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?

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.

agree unclaire、haibinyouli，选E

原文两个结论：

1、SV40 virus is a contributing cause

2、vaccine was the source of the virus found in mesotheliomas decades later

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”

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！

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！

所以，本题应该选E

欢迎指正！

[此贴子已经被作者于2005-2-5 6:10:30编辑过]

egretxm

I choose E, though I hesitated between C and E for a long time.

there are two steps reasoning here, 1, 60 percent of tissue samples from mesotheliomas, but none from healthy tissue, contain SV40 ----> the virus is the reason for the cancer. 2, the virus come from the vaccine in 1960.

the first reasoning is unwarranted. Actually, it's reasonable to think that maybe the cancer engenders SV40  in tissue samples from mesotheliomsa rather the SV40 cause the cancer.

answer E properly excludes the first posibility then supports the conclusion.

answer C repeats the premise of the second reasoning. Tough sometimes confirmation of a premise is a kind of support for conclusion, this one is not!  the premise that in 1960 some polio accine was contaminated with the virus is a known fact here.

[此贴子已经被作者于2005-2-9 12:34:32编辑过]

tqbiao

c

juningw

E。我觉得选C的nn好像是没有把整个题综合理解。

如果综合理解，本题的意思就是：

SV40.是mesotheliomas的一个原因，在mesotheliomas的样本里面，60%都有SV40。然后说，1960年，polio vaccine被感染了这种病毒。科学家们因此推测，被感染了这种病毒的polio vaccine是mesotheliomas里面SV40的起源。

c只是重复事实。但是本题的重点是假设：被感染了这种病毒的polio vaccine是mesotheliomas里面SV40的起源。

c无法有效加强这个假设。就是发现了又怎么样？就能说明是mesotheliomas里面SV40的起源？

E就很好，说明在哪些没有感染这个病毒的polio vaccine里面，mesotheliomas就没有这个病毒。

典型的无因无果！

leslie123456789

I vote for E  无因无果 在og里面时常出现  并非无关

godiex

E.

这道题可以用逆向思维。

hypothesis是说vaccine中的病毒是m中的病毒的（唯一）起源。如果要weaken hypothesis的话，就应该是：v中的病毒不是m中的病毒的唯一起源。也就是说有其他渠道的病毒进入了m。

E当中说，vaccine没有感染病毒的地方，m当中也就从没有发现病毒。从而一定程度上排除了其它渠道的可能，故加强假设。

C肯定不对。因为C当中仅仅提到vaccine，却和m没有任何关系。

haoning

我觉得还是E好。在全文中，其实什么导致了cancer并不重要，我们要加强的是 1960年的contamination是现在SV40的source.

那么我们先看 C. Recently discovered samples of the vaccine dating from 1960 still show traces of the virus.

在1960年的sample里发现virus能说明它是source吗？不能，充其量也就说明最晚在1960年，virus已经在美国的sample里出现了。

再看E: In Finland, where the polio vaccine was never contaminated, samples from mesotheliomas do not contain SV40.

Finland 没有被contaminate过 -> 现在没有SV40
美国在1960年被contaminate过了-> 现在有SV40

这不是大大的说明了1960年的contamination很可能是SV40的来源吗？

请指教！

gwanhow

我选E，因为E排除了SV40有从其它管道进入病人体内的可能，则加强了原题

“被感染的疫苗，必为唯一的病毒来源”之假设

而C仅仅只是重述原题的”前提”，并没有排除SV40从其它管道进入人体的可能 性，很明显地无support之作用。

不知道这样说对不对 和大家讨论看看~~~

gwanhow

E的选项作用为排除他因，所以更加强原题结论