The millions of calculations involved, ______ by hand, would have lost all pract

游客2023-11-18 47

问题 The millions of calculations involved, ______ by hand, would have lost all practical value by the time they were finished.

选项 A、had they been done
B、they had been done
C、having been done
D、they were done

答案 A

解析虚拟语气题。这是虚拟语气的句子，条件句使用了省略if的倒装句形式，动作与过去事实相反。

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