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标题: [求助]PREP 1 -16 [打印本页]

作者: ilovecushi 时间: 2007-10-19 13:24
标题: [求助]PREP 1 -16

16. (27621-!-item-!-188;#058&003223)

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

答案是a 為什麼不是c 呀?

作者: Whitney 时间: 2007-10-20 03:06
Therefore,
until the cost of extracting uranium from seawater can somehow be
reduced, this method of obtaining uranium is unlikely to be
commercially viable.
(C) just assume that the assumed condition is right, while we know that all assumed condition in the argument must be right.

作者: danver 时间: 2007-10-20 09:11

文章结论：除非海水提炼铀的成本降低，该获得铀的方法不太会在商业上可行。

选项a: 陆地铀矿是否枯竭决定上述结论是否成立。

陆地铀矿枯竭导致只能使用海水提炼铀的方法，所以陆地铀矿枯竭则文章结论不成立，不枯竭文章结论成立。

选项b: 加强

作者: ilovecushi 时间: 2007-10-21 02:08

謝謝樓上兩位的詳細解釋

我了解了~~

謝謝

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