作业帮doesn't,isn't,wasn't,hasn't区别以及用法
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doesn't,isn't,wasn't,hasn't区别以及用法
doesn't,isn't,wasn't,hasn't区别以及用法
doesn't,isn't,wasn't,hasn't区别以及用法
doesn't 用于第三人称,时态是现在时,帮助动词构成否定,后面接实意动词,如read,hit,pick等有具体意义的动词.
isn't也用于第三人称,时态是现在时,但由于is是系动词,就是起联系作用的,比如说He is a student,is表示“是”,如果isn't,表示不是.
wasn't是isn't的过去式,除了只用在过去的时间这点不同于is外,其他一样
hasn't是过去完成时,也用于第三人称,表示到.时还没有（做完）.,如He hasn't finished his home work until 12pm. last night.
doesn't,isn't,wasn't,hasn't他们分别是does is was has 的否定形式，要从时态上讲，
doesn't是一般现在时，实意动词否定时所用的 例如： I like Eglish. I don't like English.
而is ，was 原句必须有is, was 时，否定时才能用isn't ,wasn't,例如，He is a t...
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doesn't,isn't,wasn't,hasn't他们分别是does is was has 的否定形式，要从时态上讲，
doesn't是一般现在时，实意动词否定时所用的 例如： I like Eglish. I don't like English.
而is ，was 原句必须有is, was 时，否定时才能用isn't ,wasn't,例如，He is a teacher. He isn' t a teacher. he was given a book. 否定，He wasn't given a book.
hasn't ,也是原句有has 例如：He has learned english for three years. 否定：He hasn't learned english for three years
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关键看后面的词 如果是动词 比如read 那就doesn't 例如：he doesn't read
后面是名词 比如Jack 那就isn't 例如：he isn't Jack
如果是昨天干的事 过去了 那就wasn't,
doesn't用于单数第三人称的否定回答 isn't用于非单三的否定回答 后边那个忘了 sorry