问题描述: our teacher___be in his office because the lights off.A can't B.mustn't选哪个?为什么? 1个回答 分类:英语 2014-11-23 问题解答: 我来补答 A.can't表示否定的推测,意思是“不可能……”mustn't意思是禁止,不允许 展开全文阅读