------She looks very happy. She have passed the exam.
------I guess so. It’s not difficult after all.
A. should
B. could
C. must
D. might
网友回答
A. should
B. could
(答案→)C. must
D. might
解析：考查情态动词用法。Should have done本应该做某事实际上却未做；could have done本可以做却未做；must have done一定做了某事；might have done也许做了某事。句意：—她看上去很开心，她肯定通过了考试。—我猜是这样。毕竟试卷不难。