gwd-12-38

Q38:

Outbreaks of Rift Valley fever occur irregularly in East Africa, several years apart.  When outbreaks do occur, they kill thousands of cattle.  A livestock vaccine against the disease exists but is rarely used.  It is too expensive for farmers to use routinely, and since it is not effective until a month after vaccination, administering it after an outbreak begins helps very little.  Nevertheless, experts predict that use of the vaccine will increase significantly within the next few years.

Which of the following, if true, provides the strongest justification for the experts’ prediction?

1. Rift Valley fever is spread by mosquitoes, but each outbreak is so widespread that it is impractical to control it by using insecticides.


2. When an outbreak of Rift Valley fever occurs, unaffected countries often refuse to import livestock from the countries affected by the outbreak.


3. It would take less than a month for producers of the vaccine to adjust their production operations to cope with a large increase in demand.
   



4. Many cattle farmers in East Africa are nomadic or live in remote villages, and such farmers, who have little access to modern veterinary medicine, are particularly hard hit by outbreaks of Rift Valley fever.


5. Recently published research has shown that certain identifiable climatic conditions are almost invariably followed, within two to five months, by an outbreak of Rift Valley fever.

   Answer:

我选不出答案。　天那，怎么能有这样的事情？！

   选E

   原文推论：1）疫苗昂贵，2）疫苗使用一个月以后才生效（发病后使用效用不大）——》疫苗不常用

                     专家却说：以后这个疫苗会广泛应用，问支持专家

   E说那种病之前的2-5个月的天气条件几乎不变，就是说在这种病来之前的2-5月就可知道这种病即将爆发，然后就能用疫苗

    其他选项无关

within two to five months, by an outbreak of Rift Valley fever.　

  E说那种病之前的2-5个月的天气条件几乎不变，就是说在这种病来之前的2-5月就可知道这种病即将爆发，然后就能用疫苗　

是这样翻译吗？。　谢谢了kingsoft　。

Reasoning: and since it is not effective until a month after vaccination, administering it after an outbreak begins helps very little.

Conclusion:  Nevertheless, experts predict that use of the vaccine will increase significantly within the next few years.

it means that vaccines must be used at least one month before the outbreak. the supporting answer must be able to tell, the experts now must be able to (but couldn't in the past) predict the outbreak and use the vaccine at least one month before it happens.

   选E

   原文推论：1）疫苗昂贵，2）疫苗使用一个月以后才生效（发病后使用效用不大）——》疫苗不常用

                     专家却说：以后这个疫苗会广泛应用，问支持专家

   有一种可识别的天气条件，（只要这种天气条件发生）2－5个月后就一定会爆发Rift Valley fever。     其他选项无关

这个选项怎么就支持专家了呢？就算是2-5个月以后爆发了这个FEVER，疫苗那么贵，farmer还是用不起啊！

怎么回事呢？

如果只从一个角度就可以支持专家的话，那么C选项

要support专家的观点，有两种途径：一是对条件1的否定，即价格不贵，二是对条件２的否定，即一个月前就可以避免其作用要在一个月后才能发挥的缺点，本题E答案是对２的取非加强。