单选题 Editorial:
Critics of nuclear power complain about the allegedly serious harm that might result from continued operation of existing nuclear power plants. But such concerns do not justify closing these plants; after all, their operation has caused no more harm than that caused by pollution generated by coal and oilburning power plants, the most important other sources of energy.
Which of the following is an assumption on which the argument depends?

A、 Existing nuclear power plants should be closed only if it can be conclusively demonstrated that their continued operation is likely to cause harm more serious than the harm their operation has already caused.
B、 Closing existing nuclear power plants would require greatly increased reliance on coal and oil-burning power plants.
C、 The harm that has resulted from operation of existing coal and oil-burning power plants has been significant.
D、 The harm that a nuclear power plant is likely to cause as it continues to operate can be reliably predicted from the past history of nuclear power plants.
E、 (E) The only harm that has resulted from operation of existing coal and oil-burning power plants has resulted from the pollution generated by these plants.

【正确答案】 D

【答案解析】[解析] 寻找本题结论的假设，就是要找一个使不应当关闭核电站这个结论成立的必要条件。由题可知，本题结论成立的必要条件，就是一个能对核能批评家的态度构成反对或削弱的条件。根据以上分析可知，5个选项中只有(D)选项的内容能对核能批评家的态度构成反对，其推理如下：目前核电厂的经营产生的危害不及燃煤或燃油发电厂，而继续运行核电厂可能产生的危害又能根据它们以前的危害可靠地推出，也就是说继续运行现有的核电厂不可能会导致严重的危害，所以(D)为正确答案；(B)容易误选，因为它起到很好的支持作用，但它并不是结论成立的必要条件，因为即使违反(B)关闭核电站不大量增加对煤炭和燃油发电站的依赖，本题的推理仍然成立，所以(B)不对，(B)中的“greatly”去掉之后，则可以作为一个假设；(C)也是起到支持作用，但它也不是本题结论成立所需的必要条件，因此，也为错误选项。