1 not at all 与That's OK. That's all right. It's a pleasure.一样，是用来回答感谢、道歉的客气话，意为“不客气，没什么，没关系”。not at all 有时也表示“根本不，一点也不”。
A: Thank you for your help. 感谢你的帮助 。
B: Not at all ! 不客气 ！
A: Sorry, I am late again. 对不起，我又迟到了 。
B: Oh, not at all . Come in please. 噢，没关系，请进吧 ！
A: Is it too cold? 太冷了吗 ？
B: Not at all . 一点也不冷 。
2 not...at all 是比not更为强调的否定形式，表示“一点也不，根本不”，不可用作Thank you的答语。
The film is not interesting. 这部电影没有趣 。
The film is not interesting at all . 这部电影一点也没有趣 。
She didn't help me. 她没有帮助我 。
She didn't help me at all . 她压根儿就没有帮助过我 。
He doesn't like her. 他不喜欢她 。
He doesn't like her at all . 他根本就不喜欢她 。
3 not...very much或not...much 是一种较弱的否定形式，意为“不太多，不很多”。
I don't like it very much . 我不太喜欢它。（比较：I like it most. ）
She doesn't talk much . 她讲话不多。（比较：She talks a lot. ）
比较
He doesn't drink wine very much . 他喝酒不多。（弱）
He doesn't drink wine. 他不喝酒。（强）
He doesn't drink wine at all . 他压根儿就不喝酒。（更强）
提示
不可说not...a lot。
He doesn't like it very much . （正）他不太喜欢它。
He doesn't like it a lot . （误）