—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：“must have+动词-ed形式”表示“一定做了某事”,根据所提供的情景“She looks very happy.”可判断出她一定通过了考试。“should have+动词-ed形式”表示“本来应该做某事,而没有做”,常用于表示责备。“could have+动词-ed形式”在肯定句型中,往往用作委婉地批评，表示本应该做什么,而没做，有时也用作猜测。“might have+动词-ed形式”表示推测过去做过某事，“也许”发生了。