關係代名詞：that

只用於限定用法，代替「人」和「非人」。

The boy that [who] is playing the piano is my brother.

（正在彈鋼琴的男孩是我的哥哥。）

that前面不可有介系詞。

You are the very boy that I have been looking for.（正）

You are the very boy for that I have been looking.（誤）

（你正是我在找的那個男孩。）

先行詞有最高級形容詞時。

This is the most delicious crab burger that I have ever taste.

（這是我嚐過最美味的蟹堡。）

先行詞前有the only, the same, the very , the first, the last或all, on, little, much, none, any , every, …時，較常用that。

He was the only man that I knew in my neighborhood.

（他是我唯一認識的鄰居。）

His writing contains little that is new, but much that is old.

（他所寫的內容大多是舊的，小部分是新的。）

前有疑問代名詞，為避免who…who, which…which的重複，故用that。

Who that has read his great novels can forget his name?

（有誰能在閱讀他那部偉大小說後還能忘記他的名字？）

先行詞含有「人」和「非人」時。

Can you see a man and his dog that are crossing the bridge?

（你有看見一個男人和他的狗走過橋嗎？）

為強調句中的某一部分而用It is…that的形式。

It was Janet that broke the window.（是Janet打破了窗戶。）

what

What本身兼作先行詞的關係代名詞。

My teacher made me what I am now.（=…the man that I am now.）

（我的老師塑造我成為今日的樣子。）

I really mean what I say.（=…the thing which I say.）

（我的意思就如同我說的。）

複合關係代名詞：

在who, which, what, whose, whom加上ever即成複合關係代名詞。其本身兼做先行詞及關係代名詞。

(1)  引導名詞子句（複合關係代名詞＝先行詞＋關係代名詞）

Whoever comes will be hospitably treated.（=Anyone who comes…）

（每位來賓都將被親切的招待。）

(2)  引導副詞子句（～ever=no matter～）

Whoever（=No matter who）may say so , he will not believe it.

（無論誰說的，他都相不信。）

Whatever（=No matter what）you may say, I shall go there.

（無論你說什麼，我還是會去。）