系动词be、助动词、情态动词的否定形式一般可以缩写成为一种简略的形式。如： is not—isn’t are not—aren’thttp://yingyu.chazidian.com was not—wasn’t were not—weren’t has not—hasn’t have not—haven’t will not—won’t would not—wouldn’t shall not—shan’t should not—shouldn’t do not—don’t did not—didn’t ought not—oughtn’t dare not—daren’t used not to—usedn’t / didn’t use to