(8)当must+be表示对现在情况的推测时,简略问句的动词一般用be的相对应形式,绝对不要使用must。我们参加考试要切记这一点。
It must be Tom,
isn't it
? 那一定是汤姆,是吗?
You must be a soldier,
aren't you
? 你一定是一名战士,对吗?
John must be at home,
isn't he
? 约翰肯定在家,是吗?
They must have stayed at hotel last night,
didn't they
? 他们昨晚一定是住在旅馆里,是吗? (不能用haven't they?来提问)
She must have been to the headmaster's office,
hasn't she
? 她一定是去校长办公室了,是吗? (请将本句与上一句子对照思考)
需要注意的是:表示否定的推测时,must不能写成mustn't,我们要用can't be。
例如,我们不能说:He mustn't be a lawyer,
can he
?
我们应当说:He can't be a lawyer,
can he
? 他不可能是个律师,对吧?