關係副詞可代替的先行詞是時間、地點或理由的名詞，在從句中作狀語。
1. 關係副詞when, where, why的含義相當於"介詞+ which"結構，因此常常和"介詞+ which" 結構交替使用，例如：
There are occasions when (on which) one must yield.
Beijing is the place where (in which) I was born.
Is this the reason why (for which) he refused our offer?
關係代詞在定語從句中作賓語時，可以省略。
(1) Behind one door was a hungry tiger (that/which) the guards had put there.
(2) The tiger would immediately jump upon the poor man (whom/who) the guards had brought to the arena.
whose只用作定語,可以用來指人或物; 若指物，它還可以同of which互換, 例如：
(1) They rushed over to help the man whose car had broken down.
(2) Please pass me the book whose (of which) cover is green.
