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标题: GWD Qs---Thanks a lot [打印本页]

作者: QingHuang 时间: 2007-11-1 20:25
标题: GWD Qs---Thanks a lot

Why the answer is E? E doesn't mention "next few years" Thanks for your kind help!!

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?

Rift Valley fever is spread by mosquitoes, but each outbreak is so widespread that it is impractical to control it by using insecticides.
When an outbreak of Rift Valley fever occurs, unaffected countries often refuse to import livestock from the countries affected by the outbreak.
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.
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.
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.

作者: simonshen 时间: 2007-11-4 02:10

这题的意思先大致说下。非洲有个病，每隔几年周期性爆发一次。有种疫苗很有效，但是长期用太贵用不起，而这疫苗只有在发病前一个月注射才有效，在出现疫情后再用就没用了。根据以上信息，很显然，若能掌握这个病爆发的周期，即若能预测啥时候发病，那再发病前一个月注射一下疫苗就会很有效，这样使用这种疫苗就会多了。

看看E，最近的研究成果显示，有些可以辨识的天气状况出现后的三五个月内，这个病肯定爆发，那就是间接地给了一个参照，让人能预测这个病啥时候发生，所以逻辑上就串上了。其他几个都是无关选项。

作者: QingHuang 时间: 2007-11-4 10:22
thank you for the evplaination!

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