(1)關係代詞 e.g.:that,which,who,whom,whose etc.
(2)關係副詞 e.g.:when,where,why etc.
The woman who is standing by the classroom is our Chinese teacher.
This is the room where Bin Ladin once lived.
The girl who plays the piano very well is his girlfriend.
She is no longer the woman who she used to be.
I can't remember the man who I gave the key to.
Where is the student whom Professor Nirth praised at the meeting.
The girl with whom he was traveling is his girlfriend.
註：在「介詞提前」即「介詞+關係代詞」結構出現時，關係代詞只能用 whom 和 which 。
She is looking after the little child whose parents have gone to Singapore.
He lived in the room whose windows face south.
The man that is speaking at the meeting is a famous scientist.
Is this the teacher that you talked about yesterday.
She is no longer the girl that she was in her childhood.
The train that has just left is for Beijing.
Is this the photo that you took last summer?
I wish my home town was not a polluted place that you think it to be.
The building which stands near the train station is a company.
The computer which she wanted to buy was sold out.
She was fond of dancing,which her husband never was.
When(=at,on,in,during + which):代替時間名詞.做時間狀語:
I shall never forget the day when(on which) we moved into our new flat.
Where(=in,at + which):代替地點名詞.做時間狀語:
This is the place where(at which) John parks his car.
She didn't know the reason why(for which) she was dismissed.
as用作關係代詞和關係副詞引導限定性定語從句,並在從句中做主語,賓語,表語或狀語,構成:the...same as, such...as, so...as 等結構.
Here are such questions as are often asked by the universtiy students.
This is the same T-shirt as I have bought.
She has never seen such a handsome boy as I am.
She'll do the experiment the same way as I do.
I came the same day as he left.
She studies in the same college as he does.
She didn't believe such reason as he did so.
Here is so difficult a question as nobody can answer.
(2)引導非限定性定語從句. as引導非限定性定語從句時,代替整個主句,對其進行說明.一般用於as we all know,as is known to all,as it is,as is said above,as already mentioned above,as is usual,as is often the case,as is reported in the newspaper等句式中.as引導非限定性定語從句中做主語,表語或賓語,且引出的從句位置比較靈活,可位於句首或句尾,也可插如入主句中間.通常由逗號將其與主句隔開.as此時有"正如...","就像..."之意.
As is known to China,Qu Yuan is a great Chinese poet.
He forgot to bring his textbook with him,as was often the case.
She is absorbed in work,as she often was.
As we all know,the moon is round.