英語的否定句一定要有否定詞，例如no、not、never等。

否定句有九個分類，分別是：

（1）一般否定句

I don't know this. No news is good news.

There is no person（smoking）/not a person/not any person（smoking）in the house.

（2）特指否定

I am sorry for not coming on time.

I don't think / believe/suppose / feel / imagine you are right.

（3）部分否定

All the answers are not right.

I don't know all of them.

I can't see everybody/everything.

（4）全體否定

None of my friends smoke.

I can see nothing/nobody.

Neither of them is right.

Nothing can be so simple as this.

（5）延續否定

You didn't see him, neither/nor did I.

You don't know, I don't know either.

He doesn't know English, let alone / to say nothing of/not to speak of（更不用說）French.

（6）半否定句

We seldom/hardly/scarcely/barely hear such fine singing.

I know little English. I saw few people.

（7）雙重否定

You can't make something out of nothing.

What's done cannot be undone.

There is no sweet without sweat.

I can't help /keep/ laughing whenever I hear it.

No man is so old but（that）he can learn.

（8）排除否定

Everyone is ready except you.

He did nothing but play.

But for your help, I couldn't do it.

（9）加強否定

I won't do it at all.

I can't see it any more.

He is no longer a boy.

簡單地說就是在動詞後面加not，有is、am、are的句子會在這些詞後面加not，I am (not) a boy.沒有is、am、are的句子會在動詞前加don't或者do not，I （don't）like basketball.

如果有must、may、can這類的詞，在這類詞後面加not，I can （not ）walk.

一般是根據句子的不同情況進行改動。