Four hundred dollars for just a pair of shoes? You be joking!A. mayB. canC. can’tD. must

问题补充：

Four hundred dollars for just a pair of shoes? You be joking!

A. may

B. can

C. can’t

D. must

答案：

A. may

B. can

C. can’t

(答案→)D. must

解析：四百美元仅能买一双鞋？你一定是在开玩笑。May可能 can能 can’t不能 must必须。非常有把握的肯定性推测，要用情态动词must。