很高兴为您
Look,Sue is over there.That_______be her,She is in Canada now,
That can't be her 不可能是她 表示强烈的否定推测
mustn't 禁止、不可以 这里不符合句义
Mr Smith musr have been to your home this morning.No,he_______because he didn't know my address.
couldn't 不可能 表示强烈的否定推测
may not 也许不 同样代入句子就可以知道不符合句意.
由后面原因“他不知道地址”,可知,是”不可能来我家“
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-------------------------------谢谢你了这两道题就是通过句意来判断的嘛？ 能用语法解释吗？语法解释已经给出了，就是情态动词的用法和意义。