定語從句由關系代詞who、whom、whose、which、what、as和關系副詞where、when、why等引導，但須記住：what不能引導定語從句；關系詞的分析須考慮它在定語從句中的成分。

關系詞		先行詞	從句成分	例句	備注
關系代 詞	who	人	主語	Do you know the man who is talking with your mother?	whom, ?which和that在從句中做賓語時，常可以省略，但介詞提前時后面關系代詞不能省略，也不可以用that
	whom	人	賓語	Mr. Smith is the person with whom I am working
				The boy (whom) she loved died in the ?war..
	whose	人或物	定語	I like those books whose topics are about history.
				The boy whose father works abroad is my ?deskmate.
	that	人或物	主語，賓語	A plane is a machine that can fly.
				She is the pop star (that) I want to see ?very much.
	which	物	主語，賓語	The book (which) I gave you was worth $10.
				The picture which was about the accident ?was terrible.
	as	人或物	主語，賓語	He is such a person as is respected by all of us.	as做賓語一般不省略
				This is the same pen as I lost yesterday.
關系副 詞	when	時間	時間狀語	I will never forget the day when we met there.	可用on which
	where	地點	地點狀語	This is the house where I was born.	可用in which
	why	原因	原因狀語	I can’t imagine the reason why he turned down my offer.	可用for which

　　that與which, who, whom的用法區(qū)別

情況	用法說明	例句
只用that的情況	1.先行詞為all, everything, anything, nothing, little, much,等不定代詞時	1.He told me everything that he knows.
	2.先行詞被all, any, every, each, much, ?little, no, some, few等修飾時	2.All the books that you offered has been given out.
	3.先行詞有形容詞最高級和序數(shù)詞修飾時	3.This is the best film that I have ever read.
	4.先行詞既指人又指物時	4.We talked about the persons and things that we remembered.
	5.先行詞被the only, the very修飾時	5.He is the only man that I want to see.
	6.句中已經(jīng)有who或which時，為了避免重復時	6.Who is the man that is making a speech?
只用which, who, ?whom的情況	1.在非限制性定語從句中，只能用which指代物，用who/whom指人	1.He has a son, who has gone abroad for further study.
	2.在由“介詞+關系代詞”引導的定語從句中，只能用which指物，whom指人。	2.I like the person to whom the teacher is talking.
	3.先行詞本身是that時，關系詞用which, 先行詞為those, one, ?he時多用who。	3.Those who respect others are usually respected by others.

指人的關系代詞有who、whose、whom、that

　　The old man who/whom /that we visited yesterday is a famous artist.

　　Miss Wang is taking care of the child whose parents have gone to Beijing .

　　The man with whom my father shook hands just now is our headmaster. (=The man who/whom that my father shook hands with just now is our headmaster.)注：

　　A. 指人時有時只用who不宜用that。

　　1.先行詞為one、ones或anyone

　　(1)The comrade I want to learn from is the one who studies hard and works hard.

　　(2)Anyone who breaks the law should be punished.

　　2.先行詞為these時

　　These who are going to Beijing are the best students of our school.

　　3.在there be 開頭的句子中

　　There is a student who wants to see you.

　　4.一個句子中帶有兩個定語從句，其中一個定語從句的關系代詞是that，另一個宜用who，以免重復。

　　The student that won the first prize is the monitor who works hards.

　　5.在非限制性定語從句中

　　A。I met a friend of mine in the street, who had just come from Japan.

　　B.主句以who開頭的句子中,只用that,不用who。

指物的關系代詞有which、whose(=of which)、that

　　1. I like the books which / that were written by Lu Xun.

　　2. The desks (which/that) we made last year were very good.

　　3. This is the house in which we lived last year. (= This is the house which /that we lived in last year.)

　　4. I live in the room whose windows face south. (= I live in the room ,the windows of which face south.)

　　注：A. 介詞如果位于作為其賓語的關系代詞之前時，只能用whom、 which不能用who或that.

　　(1) The girl about whom they were talking is our monitor.

　　(2) The book in which there are many interesting things was written by Li Ming.

　　B. 部分短語動詞中的介詞不可與動詞拆開，在定語從句中其介詞不可前置，只能放在其動詞之后。

　　Is this the book which she is looking for?

　　The old man who/whom they are waiting for is Professor Li.

　　The child who/whom she is looking after is Wang Ping’s son.

　　C. 指物時，下列情況下只能用that ，不宜用which。

　　(1)先行詞為不定代詞，如All、much、anything、everything、nothing、something、none、the one等。

　　We are willing to do anything that is good to the people.

　　I have told them all (that) I know.

　　All that can be done has been done.

　　(2)先行詞是序數(shù)詞或被序數(shù)詞、修飾時。

　　The first book that I read last night was an English novel.

　　(3)先行詞是形容詞最高級或被最高級修飾時。

　　This is one of the most interesting films that I have ever seen.

　　This is the best that can be done now.

　　(4)如果有兩個或兩個以上分別表示人和物的先行詞時(先行詞既有人又有物)，定語從句的關系代詞用which和who都不合適，只能用that。

　　We know nothing about the doctors and the hospitals that you are talking about.

　　There are sheep and men that can be seen on the hill.

　　(5)如果先行詞被the only、the very、the last、the same、any、 few 、little、no、 all 、one of、 just修飾時。

　　This is the only book that can be lent to you.

　　(6)當主句是以which開頭的特殊問句時，關系代詞只用that。

　　Which is the dictionary that he used yesterday ?

　　D.只物時，下列情況下只能用which，不宜用that。

　　(1)關系代詞放在介詞之后

　　This is the factory in which we once worked.

　　(2)非限制性定語從句中

　　This is the book, which is written by Lu Xun.

　　(3)that，Those作主語時

　　Those which are on the desk are English books.

　　E.先行詞前有such、the same、 as時, 關系代詞用as，不用that, 但the same…as…表示同樣的, the same…that…表示同一的

　　He knows as many people as are present at the meeting.

　　Such people as you refer to are rare nowadays.

When/which、where /which、why

　　which I still never forget.

　　This is the day when I joined the party.

　　which he spent reading the books.

　　where I found the book.

　　which makes machines.

　　This is the place which we once visited.

　　which I will never forget.

　　which I am looking for.

　　限制性定語從句與非限制性定語從句的區(qū)別：

　　All the students who study hard have passed.學習努力的學生都考試及格了。(只有努力的及格了，不努力的沒及格。) All the students ,who study hard have passed.所有的學生都及格了，他們學習努力。(沒有人不及格，這些學生都很努力。)

　　從句是先行詞不可缺少的定語(如去掉，主句意思就不完整或不正確。) 從句是對先行詞的附加說明(如去掉，主句意思仍清楚，不受影響。) 與主句關系密切，不用逗號 與主句關系不十分密切，用逗號與主句隔開譯為漢語時，從句譯在先行詞前，與先行詞用“的”連接 譯為漢語時，從句放在主句后面關系代詞that可以代替who、whom(指人)、which(指物) 關系代詞不用that,只用who、whom(指人)、which(指物) 關系代詞代替賓語時可以省略 關系代詞不能省略關系代詞as和which

　　先看下面兩個例句：

　　1.This elephant is like a snake, as /which everybody can see. =As everybody can see, this elephant is like a snake. 任何人都看得出來，這頭象像條蛇。

　　2.Tom didn’t pass the physics exam, which made his parents very angry. Tom物理考試不及格，這使得他父親很生氣。

　　這兩個例句中，as和which所代表的都是整個主句所表示的內(nèi)容。但有兩點不同之處：

　　1. 在形式上as引導的非限制性定語從句可位于主句的后面，也可位于主句的前面;而which引導的非限制性定語從句只能位于主句的后面，不能位于主句的前面。

　　2. 在意義上，as引導的定語從句和主句的關系一般為一致關系，常譯為“正如……”，“就像……”，而which引導的定語從句和主句的關系是因果關系，或which引導的定語從句是對主句的評論。因此，在意思通順的情況下，which可代替as，而as許多時候不能代替which，如句2。再如：

　　1.He was late again, as / which we had expected. =As we had expected, he was late again. 正如我們所料，他又遲到了。/他又遲到了這是我們早就料到的。

　　2. The street hasn’t been cleared for weeks, which makes it very dirty. 街道好多星期沒有打掃了，因此整條街很臟。(不用as)

　　3.The young man cheated his friend of much money, which was disgraceful. 那年輕人詐騙了他朋友許多錢財，這是不光彩的。(不 用as)

　　4.He takes exercise everyday, which has done a lot of good to his health. 他每天運動，這對他的身體很有好處。(不用as)

　　5.As has already been pointed out, English is rather difficult for a foreigner. 正如已經(jīng)指出的那樣，英語對于初學者說，是相當難學的。在such…as…、the same…as…、 as…、 as many…/much as…等結構中,as不能用which代替。如：Such books as this are too difficult for beginners. 這樣的書對于初學的人來說是太難了。

　　“One of the +復數(shù)名詞”后面定語從句中謂語單復數(shù)情況

　　這一結構后面的定語從句的謂語動詞通常用復數(shù)形式，跟定語從句所*近的那個復數(shù)名詞在數(shù)上保持一致。如：That is one of the books that are required for study at school.

　　如果one of +復數(shù)名詞這一結構前面帶有the only、the very之類的限定語，后面定語從句的謂語動詞則要用單數(shù)形式，這是因為定語從句在意義上修飾的是而不是那個復數(shù)名詞。如：

　　1.He is the only one of the teachers who knows French in our school.( 修飾the only one)

　　He is one of the teachers who know French in our school.( 修飾the teachers)

　　2.This is the only one of the rooms that is free now. (修飾the only one)

　　This is one of the rooms that are free now. (修飾rooms)

　　as與which引導的定語從句

　　兩者均可引導非限制性定語從句，有時可以互換，但下列情況多用as。

　　1. 關系代詞引導的定語從句居句首時。 As we all know, the earth is round.

　　2. 當與such或the same連用時，一般用as。 Such books as you tell me are interesting. I have the same plan as you.

　　3. 當從句和主句語義一致時，用as，反之則用which。 She has married again, as was expected. She has married again, which was unexpected.

　　4. as在從句中作主語時，后面常接行為動詞的被動語態(tài)，如be known，be said，be reported等，如從句中行為動詞是主動語態(tài)，一般要用which作主語。

　　She has been late again, as was expected.

　　Tom has made great progress, which made us happy.

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