单选题 The millions of calculations involved, had they been done by hand, ______ all practical value by the time they were finished.

A、 could lose
B、 might lose
C、 would have lost
D、 ought to have lost

【正确答案】 C

【答案解析】虚拟语气用在条件句中表示对过去的假设，从句使用过去完成时，主句使用“would(should， could，might)+have done"，如：If natural resources had been fully utilized，industry would have developed more rapidly．如果自然资源得到了充分利用，工业的发展本可以更快些。