Question

高中情态动词题

1，your sister must be at home,_______she?
A,isn't Bdoesn't Cmustn't can't
2,they had to catch the early bus,________they?
Ahadn't Bdidn't Cmustn't Dcan't
3,He must have been abroad,_______he?
Ahaven't Bhasn't Cisn't Ddidn't
请问关于情态动词的反义疑问句怎么判断，
希望有详细的解释
谢谢

Answer 1

1. A your sister must be at home. 这里MUST表推测，相当于your sister is at home. 反义疑问句，前肯后否，所以用isn't
2. B。 they had to catch the early bus 这里had to 是必须的意思，过去时态，用do的过去时态，前肯后否，所以用didn't
3. B He must have been abroad，这里MUST表推测，相当于He has been abroad.反义疑问句，前肯后否，所以用hasn't