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题库 / Prep2007E1-CR-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?
Whether the uranium in deposits on land is rapidly being depleted
Whether most uranium is used near where it is mined
Whether there are any technological advances that show promise of reducing the cost of extracting uranium from seawater
Whether the total amount of uranium in seawater is significantly greater than the total amount of uranium on land
Whether uranium can be extracted from freshwater at a cost similar to the cost of extracting it from seawater
P: 从海水中提取uranium的成本比目前市场上uranium的价格都高
C:除非有办法降低海水提炼的成本，否则这种办法不太可能商业化
逻辑链把海水提炼的成本看成是影响新方法可行性的唯一条件，choice a,是否uranium在地球上的储量全部耗尽了。correct，如果地球上的存量耗尽，那就不得不从海水中寻找。说明除了价格以外，还有其他因素能够决定新方法是否可以实行 。---by ruqi
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