【题目】—With the failure of the experiment, we reach a dead end.
—Cheer up! Many good things would never have happened if the bad events ________ first.
A. don’t happen B. didn’t happen
C. hadn’t happened D. haven’t happened
在线课程【答案】C
【解析】表示与过去事实相反的推测时，主句用would have done的形式，if从句用过去完成时。