prep的一道题

猫小雯雯

Most of the world's supply of uranium currently comes from mines.  It is possible to extract uranium from seawater, but the cost of doing so is greater than the price that uranium fetches on the world market.  Therefore, until the cost of extracting uranium from seawater can somehow be reduced, this method of obtaining uranium is unlikely to be commercially viable.（A）

Which of the following would it be most useful to determine in evaluating the argument?

A. Whether the uranium in deposits on land is rapidly being depleted  

B. Whether most uranium is used near where it is mined  

C. Whether there are any technological advances that show promise of reducing the cost of extracting uranium from seawater  

D. Whether the total amount of uranium in seawater is significantly greater than the total amount of uranium on land  

E. Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater
想问C为什么排除呢？虽然我觉得A也不能去掉，但是不明白C的不对是在哪里，谢谢

vampire_lily

我觉得是因为提干中说了until cost can be reduced,就是相当于已经排除了这个gap
如果是直接说therefore, this method of obtaining is not commercially viable，那c也可以是对的啦~
不知道这样理解对不对

猫小雯雯

vampire_lily 发表于 2014-8-26 10:54
我觉得是因为提干中说了until cost can be reduced,就是相当于已经排除了这个gap
如果是直接说therefore, t ...

谢谢LILY~~解决我的困惑

vampire_lily

猫小雯雯 发表于 2014-8-26 20:40
谢谢LILY~~解决我的困惑

hiahiahia...第一次给别人回答问题

keruan

FOR C, if "there are technological advances that show promise of reducing the cost of extracting uranium from seawater " the conclusion could be true, because this one do not mention how much it could reduce the cost of extracting uranium from seawater, maybe only 0.1%. if there no such promise exist the conclusion could also be true. So C is not the most useful answer to determine in evaluating the argument.