问题补充：
----I passed the college entrance examination.
----Congratulations! You.
A. could have studied hard
B. must have studied hard
C. should have studied hard
D. might have studied hard
答案：
A. could have studied hard
(答案→)B. must have studied hard
C. should have studied hard
D. might have studied hard
解析：考查情态动词用法。could have done本可以做某事，实际上却未做；must have done一定做了某事；should have done本应该做某事，实际上却未做；might have done也许做了某事；句意：—我通过了高考。—祝贺你。你一定学习得非常认真吧！根据句意说明是对过去所发生的事情的有把握的肯定推测，故B正确。
