Tom is a top student in our class Howit be that he was a failure in the last exam?A. ca

问题补充：

、Tom is a top student in our class , Howit be that he was a failure in the last exam?

A. can

B. should

C. may

D. nust

答案：

A. can

(答案→)B. should

C. may

D. nust

解析：考察情态动词用法。本句中的should并不表示“应该”，而是表示“竟然”指的是意料之外的事情。句意：Tom是一个优秀生，他怎么可能竟然会在上次考试里不及格呢？根据句意说明B正确。