否定用字包括not, never, no, none, neither, nor, nothing but等。
1. not：not為否定副詞，其功用為
(a)幫助動詞變成否定式
b)後面跟名詞，表達”不是”
例：1. His idears are not clearly expressed.
2. Not everyone agrees with him. (不是)
2. never：never為否定副詞，幫助動詞成為否定式，若擺在句首，則後面的子句應用倒裝結構。
例：1. We will never forget his kindness to us.
2. Never have I met such a kind person.
3. no：no為形容詞，後面接名詞，表達”沒有”。
例：1. There is no water.
2. He has no sympathy for the poor.
4. none：none純為名詞功能，後面不能再接名詞。
例：1. None of the girls like him.
2. Jane likes none of the books.
5. nothing but = only(只不過是)
例：1. Don’t trust him；he is nothing but a liar.
6. neither-nor：neither與nor可以連用，即”neither A nor B”，表示”非A也非B”，A與B在結構上要平行對稱。另外，neither與nor若單獨使用，表達”也不”，引導子句，且要使用倒裝結構。
例：1. Neither John nor his brother can speak English.
2. He can neither swim nor play the piano.
3. He doesn’t like mathematics, and neither do I.
4. I haven’t read that book, and nor has John.
