should,would,could,must,might,may,can有什么区别答:---Well, I must have been sleeping, so I didn't hear it.5) 否定推测用can't。If Tom didn't leave here until five o'clock, he can't be home yet. 如果汤姆五点才离开这儿,他此时一定还未到家。5 表示推测的用法 can, could, may, might, must 皆可表示推测,其用法如下:1...