【题目】Had they known what was coming next, they _________second thoughts．
A．may haveB．could have
C．must have hadD．might have had
在线课程【答案】D
【解析】
选D，本题考查虚拟语气的用法。本句是一个倒装句，可还原为：if they had known what was coming next, they might have had second thought。根据had known提示，可知是与过去事实相反，因此虚拟语气主句中应该用would/might have done，由此可见答案D符合语境。