does not=doesn't. 是助动词do笫三人称单数一般现在时的否定式。本身无词义。如：He doesn't go to school by bus every day.She doesn't like English.Cannot=can't.汉语翻译为不能、不可以，表示很语气坚决。例如：I cannot believe this！ 我无法相信！She can't dress herself because she is only two.
