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: 我来补答 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 展开全文阅读