They must be waiting for us,()?a.aren't they b.mustn't they

问题描述:

They must be waiting for us,()?a.aren't they b.mustn't they 求辨析
1个回答 分类:英语 2014-09-26

问题解答:

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情态动词的反义疑问句,must的反义疑问句固定,根据后面所跟的动词来觉得,此处是be动词,所以就是aren't they
 
 
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