问题
选择题
Experiments of this kind ___in both the U．S and Europe well before the Second World War．
A．had conducted
B．have conducted
C．have been conducted
D． had been conducted
答案
答案：D
题目分析: 考查动词时态。根据before the Second World War可知此处是指过去的过去，应该用过去完成时；而experiment和conduct是被动关系，所以用过去完成时的被动形式,故答案选D。句意：二战前就在美国和欧洲进行过这种实验。
