问题
选择题
—Why does Sara know so much about Angkor Wat?
—She _______ there,or she may have read about it.
A．must have been
B．shouldn’t have been
C．may have been
D．can’t have been
答案
C
此题考查情态动词表推测的用法。由后面or...来判断，说话人对此事不是很有把握，故用may have done表示对过去情况不太肯定的推测，意为“或许做了某事”。must have done用于肯定句，表示对过去情况肯定的推测，意为“一定发生了某事”。