问题详情：
—She looks very ________ have passed the exam.
—I guess 's not difficult after all.
A．should B．could
C．must D．might
【回答】
C 考查情态动词。should have done意为“本应该做却未做”；could用于对过去的否定推测，couldn't have done意为“不可能做过”；must have done表示对过去的肯定推测，意为“肯定做过……”；已经做过……”；might have done意为“可能已经做过”。上句意为：她看起来很高兴。她肯定是通过了考试。故选C。
知识点：情态动词
题型：选择题
