He must be helping the old man to water the flowers, （）?
A、
is he
B、
isn't he
C、
mustn't he
D、
must he
【正确答案】：B
【题目解析】：
反义疑问句的用法。
He must be helping the old man to water the flowers, （）?
He must be helping the old man to water the flowers, （）?
is he
isn't he
mustn't he
must he
反义疑问句的用法。