※ 引述《CGHS13 (.......)》之铭言： : Most of the world's supply of uraium currently from mines. It is possible to : extract uranium from seawater, but the cost of doing so is greater than the : price that uranium fetches in the world market. Therefore, until the cost of : extracing uranum from seawater can somehow be reduced, this model of obtaning : uraium is unlikely to be commercially viable. : which of the following would it be most useful to determine in evaluating : the arugment? : The answer is A : Whether the uraium in deposit on the land is rapidly being depleted. : 这个答案我可以理解 : but the answer C : Whether there are any technological advances that show prmise if reducing the : cost of extracing uraium from seawater. : 为什麽这个不行阿? 题目原意是大部分现在U的供给来自矿物的开采 但是有另一种来源是海底蕴藏 但是这种来源要取得U要花比在市场卖出价格更高的成本 因此只有在成本降低的情况下 这种海底开采的方式才可能有办法(有人愿意)执行 题目问evaluate 而这种题目是考与假设很类似的概念 只是不一定要成立 所以呢重点在於 原本陆地上如果还有充沛的蕴藏量 要不要去用海底开采就不是所关切的焦点了 而C选项海底开采技术的进步 并非使本文成不成立的关键点 一但确定陆地上蕴藏不够 即使技术不佳(无法降低成本)也是要用这种方法 就不会有本文推论的 this model of obtaning uraium is unlikely to be commercially viable --

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