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标题: GWD01 一些疑问 [打印本页]

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作者: lujennifer    时间: 2009-9-20 18:45
标题: GWD01 一些疑问

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?

 

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 traces 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.

答案是E  为什么E比C好呢

Q14:

Yeasts capable of leavening bread are widespread, and in the many centuries during which the ancient Egyptians made only unleavened bread, such yeasts must frequently have been mixed into bread doughs accidentally.  The Egyptians, however, did not discover leavened bread until about 3000 B.C.  That discovery roughly coincided with the introduction of a wheat variety that was preferable to previous varieties because its edible kernel could be removed from the husk without first toasting the grain.

 

Which of the following, if true, provides the strongest evidence that the two developments were causally related?

 

1. Even after the ancient Egyptians discovered leavened bread and the techniques for reliably producing it were well known, unleavened bread continued to be widely consumed.
2. Only when the Egyptians stopped the practice of toasting grain were their stone-lined grain-toasting pits available for baking bread.
3. Heating a wheat kernel destroys its gluten, a protein that must be present in order for yeast to leaven bread dough.
4. The new variety of wheat, which had a more delicate flavor because it was not toasted, was reserved for the consumption of high officials when it first began to be grown.
5. Because the husk of the new variety of wheat was more easily removed, flour made from it required less effort to produce.

看了哪个都不觉得太靠谱， 请指点做题思路

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