陈述的否定句和否定回答缩写与否都可以，不过一般在否定回答时多用缩写形式，另外，am和not无论什么情况下是绝对不能缩写的。还有反义疑问句的后半部如果是否定形式是必须缩写的。

否定句的形式有哪些

（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

He went to his office, not to see him.

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

All is not gold that glitters

I don't know all of them.

I can't see everybody/everything.

Both of them are not right.

（4）全体否定

None of my friends smoke.

I can see nothing/nobody.

Neither of them is right.

Nothing can be so simple as this.

（5）延续否定

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（更不用说）French.

（6）半否定句

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

I know little English. I saw few people.

（7）双重否定

You can't make something out of nothing.

What's done cannot be undone.

There is no sweet without sweat.

No gain without pains.

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）加强否定

I won't do it at all.