He must be helping the old man to water the flowers, ()?
A.正确答案Bis he
B.isn't he
C.mustn't he
D.must he
He must be helping the old man to water the flowers, ()?
He must be helping the old man to water the flowers, ()?
A.正确答案Bis he
B.isn't he
C.mustn't he
D.must he