Question

Had they known what was coming next, they ___________ second thoughts.

A．may have

B．could have

C．must have had

D．might have had

Answer 1

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。