PREP CR1-16

buttonwood

16.
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.



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
为什么选A呢？对原文中能起到什么作用呀？请教各位牛人～

sorcerer

同问啊，C为何不行？

rebecw

为什们不选C呢？C不是一个说明cost下降的选项吗？

buttonwood

It really helps. Thank you~

sayysong

論點:


          當 從海水提煉 uranium 變便宜 --> 開始使用這個提煉技術
            
          否則 xxx assumption -> 從Mine取得 uranium




所以, 要符合整個論點, xxx 這個 assumption 就不可少.
而這個 assumption 就是: 還有足夠的Mine讓我們去得到 uranium


所以, 要 evaluate 就是問: 何時會用完?


Hope helps~


Alex