扫描二维码，直接登录
题库 / GMATLA-CR-107
Rabbits were introduced to Numa Island in the nineteenth century. Overgrazing by the enormous population of rabbits now menaces the island's agriculture. The government proposes to reduce the population by using a virus that has caused devastating epidemics in rabbit populations elsewhere. There is, however, a chance that the virus will infect the bilby, an endangered native marsupial. The government's plan, therefore, may serve the interests of agriculture but will clearly increase the threat to native wildlife.
Which of the following, if true, most seriously weakens the argument?
There is less chance that the virus will infect domestic animals on Numa than that it will infect bilbies.
There are no species of animals on the island that prey on the rabbits.
Overgrazing by rabbits endangers many of the plants on which bilbies feed.
The virus that the government proposes to use has been successfully used elsewhere to control populations of rabbits.
There is no alternative means of reducing the rabbit population that would involve no threat to the bilby.
这道题的argument是: 因为virus可能会伤害到当地的bilbie,所以实施方案的话会INCREASE增加当地物种的风险。核心是风险是否增加，而不是其他评论提到的好处坏处。我们脑子里要想的是: 就算实施了风险也只是相等，或者更小。选项C提到了目前的BILBIE的风险已经很高，所以正确，即：本来的风险都很高（食物被兔子吃掉，Bilbie也会没吃的），我现在放进一个virus，也就是有可能使得Bilbie感染而已，都是要灭绝，何来风险INCREASE一说？ E选项说的是: 所有减少兔子的方法都有风险。这个选项没提到实施前后风险的变化，可能有很多低风险的方案，也有高风险的。所以E选项肯定不对。
(C):兔子的overgrazing会危害到bilbies吃的植物。因此即便不引入virus控制兔子数量，bilbies在兔子泛滥的情况下也会因为食物减少而遭殃
方案A：实施该方案会有坏处B
反驳：不实施该方案也会有坏处B
因果推理
P: The virus will infect bilby, an endangered native marsupial.
C: Using the virus will increase the threat of native wildlife.
C选项说明在用virus之前bilby就已经被兔子威胁到了，用virus会同时感染bilby和减少兔子数量，正负作用都有，不能说一定增加威胁
issue： proposal有坏处weaken -->不实施方案a还是有坏处（另外的）
不实施方案，bilby也会有别的危害
观点: 方案a有XX坏处
削弱: 不实施方案a还是有XX坏处
找的是五个选项中的最优解，而非完美解。从该选项，可以削弱，该方案对生物的不良影响
注意：反驳一个plan的具体效果的时候
可以直接否定这个效果 或者指出另一种因素使这个效果不确定就ok了
Overgrazing by rabbits endangers many of the plants on which bilbies feed. 所以减少兔子数量对bibies也有好处