The calculations, had they been done by hand, all practical value by the time they were fi

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A. had lost
B. would lose
C. should have lost
(答案→)D. would have lost
解析：
试题分析:句意：这些计算如果用手工进行的话，那么当他们完成后将失去所有的实际价值。句中had they been done是if they had been done的省略，是对过去的虚拟，所以主句谓语应该用would have done，选D。