问题
选择题
—Mary’s score on the test is the highest in her class.
—Really? She have studied very hard.
A．may
B．ought to
C．must
D．should
答案
答案：C
考查情态动词表示推测。Must have done一定做了某事；B=D，所以排除。May have done也许做了某事；句意：—Mary的考试分数是班级里最高的。—真的吗？她肯定学习的非常认真。