He must be in his room now ,-----?

He must be in his room now ,___B__?A。mustn't B。isn't he 本题选B,因为这句中的情态动词must（肯定,一定）是用来表推测,而 must表推测时,反意疑问句应该看must后面的词,而不用must本身。-----------高三英语教师在线