问题
选择题
Experience 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
答案
D
搜题请搜索小程序“爱下问搜题”
Experience 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
D