Offshore oil-drilling operations entail an unavoidable risk of an oil spill,but importing oil on tankers presently entails an even greater such risk per barrel of oil. Therefore, if we are to reduce the risk of an oil spill, we must invest more in offshore operations and import less oil on tankers.
which of the following, if true, most seriously weakens the augument above?
A. Tankers can easily be redesigned so that their use entails less risk of an oil spill
B. Oil spills caused by tankers have generally been more serious than those caused by offshore operations.
C. The impact of offshore operations on the environment can be controlled by careful management.
D. Offshore operations usually damager the ocean floor, but tankers rarely cause such damage.
E. Importing oil on tankers is currently less expensive than drilling for it offshore.
答案是A。在C选项中说的是environment的问题，我在做题的时候把C排除是因为觉得这个与risk无关，而OG得解释是C选项支持了结论。 而D中的damage the ocean floor ,OG说的就是这个与risk是无关的，是无关选项。我在有几道题中都遇到了这种情况。于是我的总结得是：结合题目来谈，因为drill的risk比进口少，所以应该多drill少进口。C选项虽然说不是这个risk，但是它说明了offshore operation的另外一方面的优势，所以是加强。而D选项是tanker与offshore operation 比较起来的优势，那么，要削弱的话，必须是与risk有关的，所以是无关的。结论：在weaken题目中，正确的weaken选项无疑，必须是与argument的推理，focus相关的，而如果选项中出现了与focus无关的，（好比这里的environment），则不一定是无关选项，因为有也可能是支持结论的（虽然这同无关一样，都是错误选项）
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发表于 2010-3-4 21:15:13
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楼主
我在发帖的时候本来也是想在最后写一句：“其实把C看做事无关选项更容易排除”。但最终没有写是因为现在还没考试嘛，尽量去符合ETS的思路。