Experiments of this kindin both the US．and Europe well before the Second World War．A. hav

发布时间：2020-08-16 19:22:27

Experiments of this kind    in both the U．S．and Europe well before the Second World War．
A. have conducted
B. have been conducted
C. had conducted
D. had been conducted

网友回答

A. have conducted
B. have been conducted
C. had conducted
(答案→)D. had been conducted
解析：本题考查时态。根据句中时间状语before the Second World War可知用过去完成时，由于experiments与conduct为被动，故选D。
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