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）when, where, why
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.任何人都有不得不屈服的`時候。
beijing is the place where (in which) i was born.北京是我的出生地。
is this the reason why (for which) he refused our offer?這就是他拒絕我們幫助他的理由嗎？
2）that代替關係副詞
that可以用於表示時間、地點、方式、理由的名詞後取代when, where, why和"介詞+ which"引導的定語從句，在口語中that常被省略，例如：
his father died the year (that / when / in which) he was born.他父親在他出生那年逝世了。
he is unlikely to find the place (that / where / in which) he lived forty years ago. 他不大可能找到他四十年前居住過的地方。
定語從句的知識點
1. where指地點，在定語從句中做地點狀語用來表示地點的定語從句。
(1) Shanghai is the city where I was born.
(2) The house where I lived ten y ears ago has been pulled down.
2. when引導定語從句表示時間。在定語從句中做時間狀語也可做連線詞用
(1) I still remember the day when I first came to the school.
(2) The time when we got together finally came.
[注]表示時間"time"一詞的定語從句只用when引導，有時不用任何關係代詞，當然也不用that引導。
By the time you arrived in London, we had stayed there for two weeks.
到你到達倫敦的時候，我們在那裡已經待了兩個星期。
I still remember the first time I met her. 我仍然記得我第一次見到她。
Each time he goes to business trip, he brings a lot of living necessities, such as towels, soap, toothbrush etc。
每一次他去出差，他帶來了生活必需品，如毛巾，肥皂，牙刷等，很多。
3. why指原因 在定語從句中做原因狀語
(1) Please tell me the reason why you missed the plane.
(2) I don't know the reason why he looks unhappy today.
注意：關係副詞引導的從句可以由"介詞+關係代詞"引導的從句替換
(1) The reason why/ for which he refused the invitation is not clear,
(2) From the year when/in which he was going to school he began to know what he wanted when he grew up.
注：1）介詞後面的關係代詞不能省略。
2）that前不能有介詞。
3） 某些在從句中充當時間，地點或原因狀語的"介詞+關係詞"結構可以同關係副詞when ,where和why 互換。
This is the house in which I lived two years ago.
This is the house where I lived two years ago.
Do you remember the day on which you joined our club?
Do you remember the day when you joined our club?
This is the reason why he came late.
This is the reason for which he came late.
