定語從句中的關系副詞有三個：when, where和why，它們在定語從句中分別作時間、地點和原因狀語。其句法結構如下：
1. when指時間，在定語從句中作時間狀語。
例句：I still remember the day when I first came to Beijing.
I’ll never forget the day when I joined the army.
2. where指地點，在定語從句中作地點狀語。
例句：The factory where his father works is in the west of the city.
This is the house where I lived two years ago.
關系副詞“when”、“where”既可引導限制性定語從句，也可引導非限制性定語從句。
例如：I will always remember the day when I first visited the Great Wall.
He came to Shanghai in 1980, when he was only 12.
I don’t know the exact spot where they will meet.
Mr Wang will fly to Beijing, where he will stay for three months.
有時關系副詞“when”、“where”引導的限制性定語從句和先行詞有間隔的現象，是為了平衡句子的語法需要。
Do you remember one afternoon ten years ago when I came to your house and borrowed a diamond necklace?
The days are gone forever when the Chinese people used “foreign oil.”.
3. why只用于reason之后的限制性定語從句中,在定語從句中作原因狀語。
例句：That is the reason why I did the job.(在現代英語中why可以省略)
上句也可以這樣表示：
That is the reason I did the job.
又如： This was the reason (why )we raised the temperature.
關系副詞在定語從句中的用法看似簡單，以下注意點不可忽視：
1）“when”、“where”和“why”的運用取就于表時間的名詞、表地點的名詞和表原因的名詞reason在定語從句中所作的成分，比較下面的幾組句子：
*I will never forget the day when I first met you on the seashore.
*I will never forget the days which/that we spent together in Xueyao Middle School.
**This is the hospital where my mother works.
**This is the hospital which/that we visited the day before yesterday.
***The reason why he did not go to school is that he was ill.
***This is the reason which/that he gave his boss in the office .
2) “when”、“where”和“why”都可以替換成“介詞 + which”，介詞的選用取就于先行詞和定語從句中的動詞。例如：
Do you still remember the day on which we first met in Nantong?(on which=when)
This is the room in which we lived last year.(in which=where)
Do you know the reason for which he refused to go to Mary’s birthday party. (for which=why)
英語中的關系副詞由：where,when和 why。這三個關系副詞很多情況下，都可以用介詞+關系代詞來替換。
where=in /at /to+which;
when=in /on /at+which;
why=for +which.
有時定語從句中介詞短語和動詞有意義緊密的修飾關系，尤其在非限制性定語從句中，常使用“介詞 + which”結構，而不使用關系副詞。例如：
My mother works in a factory, in front of which there is a small river.
At night the soldiers got to a small hill, at the foot of which stood a farmhouse.
3) “that”可活用為關系副詞，相當于“when, where、why”和“介詞 + which”結構，尤其在“the time when”等結構中的“when”常被“that”代替，而且“that”往往省略。
I may leave here any time I want to.
During the time I was there I visited him twice.
This is my second time I have come to your country.
1.It’s helpful to put children in a situation they can see themselves differently.
A. that B. when C. which D. where
答案 D
解析 考查定語從句。先行詞是situation，指物，亦可指地點，關系詞在從句中做地點狀語，用關系副詞where，選D。
2. I have reached a point in my life ______ I am supposed to make decisions of my own.
A. which B. where C. how D. why
答案 B
3 .After graduation she reached a point in her career she needed to decide what to do.A.that B.what C.which D.where
答案 D
解析 本題考查定語從句關系詞的確定。英語中，point/situation/case等作先行詞，其后的關系詞在定語從句中作狀語時，用關系副詞where（相當于in which）。該定語從句缺少地點狀語，因此用where。
4.Life is like a long race _____we compete with others to go beyond ourselves.
A. why B. what C. that D. where
答案 D
5.Occasions are quite rare I have the time to spend a day with my kids.
A.who B.which C.why D.when
答案 D