问题补充:
He must have been late for the conference yesterday, ?
A. didn’t he
B. hasn’t he
C. mustn’t he
D. wasn’t he
答案:
A. didn’t he
B. hasn’t he
C. mustn’t he
(答案→)D. wasn’t he
解析:用must have done表示“对过去加以推测时”,其附加疑问部分要根据must后的动词形式和有无时间状语来确定用相应的时态。此句中动词是be,时间是yesterday,所以用wasnt he。如果去掉yesterday,就应选B项。