1、看句中有無(wú)be動(dòng)詞，如有，直接在be動(dòng)詞后+not。2、看句中有無(wú)情態(tài)動(dòng)詞，如有，直接在情態(tài)動(dòng)詞后+not。3、如上述二者都沒(méi)有，就應(yīng)用助動(dòng)詞+not。4、原句中動(dòng)詞假如發(fā)生變化就要恢復(fù)成原形。

一、有be動(dòng)詞(am、is、are)和情態(tài)動(dòng)詞(can、could、may、must、shoud、will、would等)時(shí)，直接在be動(dòng)詞和情態(tài)動(dòng)詞后面加not，some變?yōu)閍ny，and變?yōu)閛r，too變?yōu)閑ither，其他的照抄。

例如:

①、I am a student. – I am not a student.

②、Amy is a good girl.–Amy is nota good girl.

③、These flowers are very beautiful.–These flowersare not very beautiful.

④、I can swim.–Ican't(can not)swim.

⑤、There are some books on the table.–There are not anybooks on the table.

⑥、Jack is a doctor , too.–Jack is not a doctor , either.

⑦、I was a student ten years ago.–I was nota student ten years ago.

注:⑴、 some 、and 用于肯定句中，any、or用于否定句和疑問(wèn)句中。

⑵、was是is和are的過(guò)去式，were是are的過(guò)去式。

二、沒(méi)有be動(dòng)詞(am、is、are)和情態(tài)動(dòng)詞(can、could、may、must、shoud、will、would等)時(shí)，在動(dòng)詞前面加don't、doesn't、didn't，動(dòng)詞恢復(fù)成原型，some變?yōu)閍ny，and變?yōu)閛r，too變?yōu)閑ither，其他的照抄。

例如:

①、I like math.–I don't likemath.

②、Jack likes math, too.–Jack doesn't like math , either.

③、They like bananas and apples.–They don't like bananas orapples.

④、Lily gets up at six every morning.–Lily doesn't getup at six every morning.

⑤、His father likes playing football.–His father doesn't likeplaying football.

⑥、I went fishing yesterday.–l didn't gofishing yesterday.

注:⑴、當(dāng)句子是一般過(guò)去時(shí)態(tài)時(shí)，在動(dòng)詞前加didn't，動(dòng)詞恢復(fù)成原型。

⑵、當(dāng)句子是一般現(xiàn)在時(shí)態(tài)時(shí)，主語(yǔ)是第三人稱(chēng)單數(shù)時(shí)，在動(dòng)詞前加doesn't，動(dòng)詞恢復(fù)成原型;主語(yǔ)不是第三人稱(chēng)單數(shù)時(shí)，在動(dòng)詞前加don't。