[求助]OG11th-CR40

Offshore oil-drilling operations entail an unavoidable risk of an oil spill, but importing oil on tankers presently entails an even greater such risk oer barrel of oil. Therefor , if we are to reduce the risk of an oil spill without curtailing our use of oil, we must invest more in offshore operations and import less oil on tankers.

Which of the following, if true, most seriously weakens the argument above?

答案是A. Tankers can easily be redesigned so that their use entails less risk of an oil spill.

不太明白关于D的解释

D. Offshore operations usually damage the ocean floor, but tankers rarely cause such damage.

解释为：While offshore operations may cause other environmental damage, this point doesnot weaken the argument about oil spills.

既然offshore operations可能会导致其他损害，不就应该减少其应用，那不就是weaken the argument？

这个augue的中心是oil spills，d说的状况，是个无关项。

削弱题就是要求我们要有针对性。

D说的是其他的环境问题，偏离了题干中的oil spill

weaken argument 可以理解为 weaken conclusion  可是conclusion 不是半句话， 是therefore后面整个内容， 包括oil的目标。

所以 用A不用B是 针对以个角度来说的， 

举个例，  我认为逻辑上面FEIFEI比较细心，  你反驳我说他吃饭的时候撒了一桌，  是丝毫动摇不了原结论的