If we adequate preparations, the conference wouldn’t have been so successful.
A. haven’t made
B. wouldn’t make
C. didn’t make
D. hadn’t made
网友回答
A. haven’t made
B. wouldn’t make
C. didn’t make
(答案→)D. hadn’t made
解析：考查虚拟，由后面的句子the conference wouldn’t have been so successful.所以是对过去的一种虚拟，所以选D，句子意思“如果我们没有做好充分准备，这次会议就不会如此成功”