34. --Mary, how did your Math test go?
--I had thought I _________, but in fact I came in the top 10 in my class.
A
should have failed
B
couldn’t have failed
C
might have failed
D
shouldn’t have failed
might have done 表示对过去事情的不肯定推断;故选项C正确。
根据后半句“but in fact I came in the top 10 in my class”可知,前半句为不肯定的推测。
对情态动词表推测的用法不熟悉致错。