请教GWD里面的问题

际遇2011

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 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.
• 答案是E
• Q40:
  Insect infestations in certain cotton-growing regions of the world have caused dramatic increases in the price of cotton on the world market.  By contrast, the price of soybeans has long remained stable.  Knowing that cotton plants mature quickly, many soybean growers in Ortovia plan to cease growing soybeans and begin raising cotton instead, thereby taking advantage of the high price of cotton to increase their income significantly, at least over the next several years.
  Which of the following, if true, most seriously weakens the plan’s chances for success?
  • A.The cost of raising soybeans has increased significantly over the past several years and is expected to continue to climb.
  • B.Tests of a newly developed, inexpensive pesticide have shown it to be both environmentally safe and effective against the insects that have infested cotton crops.
  • C.In the past several years, there has been no sharp increase in the demand for cotton and for goods made out of cotton.
  • D.Few consumers would be willing to pay significantly higher prices for cotton goods than they are now paying.
  • E.The species of insect that has infested cotton plants has never been known to attack soybean plants.
  • 答案是B，为什么C不对呢？
  • 请大神们详尽解释下，不甚感激！！！
    
  
  

云游

Remmber the first objective to tackle every weaken and strengthen question is to find the conclusion.

In Q 9, the conclusion is vaccine is the source of virus. To support this conclusion we'll have either to elminate some possible logical hindrance or give an additional example. Choice E is the right answer because it has give an supportive example--in finiland without vaccine without virus, which in other words is vaccine would brought virus.

In the second question, the main plan(conclusion) is to cultivate soybean instead of cotton to make profit in the next few years. C is nonsensial beacause it says past five years. B does weaken the plan for it brings up a new possiblity that contradicts the motivation of doing so. If the infectious diseases can be controlled with the least cost, then planting cotton also remains profitable.