----- Mary looks very upset. She _______ failed to pass the exam.
----- I guess so. It's very difficult after all.
A. must have | B.could have | C.should have | D.might have |
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----- Mary looks very upset. She _______ failed to pass the exam.
----- I guess so. It's very difficult after all.
A. must have | B.could have | C.should have | D.might have |