一.基本概念
1.定語從句的定義：用作定語的從句叫定語從句。
2.先行詞：被定語從句所修飾的名詞或代詞。
3.定語從句的位置：緊跟先行詞(名詞或代詞)之後。
4.引導詞：引導定語從句的詞(包括關係代詞和關係副詞)。
﹙1﹚關係代詞：that/who/whom/which/as
﹙2﹚關係副詞：when/where/why
5.引導詞的位置：位於定語從句之前(先行詞之後)。【as除外】
6.引導詞的功能(作用)：
﹙1﹚連線先行詞和定語從句。
﹙2﹚在定語從句中充當一定的成分(關係代詞充當主語或賓語，關係副詞充當狀語)。
7.定語從句的型別：
﹙1﹚限定性定語從句(主句和定語從句之間無逗號)。
① 直接由引導詞引導定語從句
The man who you’re talking to is my friend.
② 由介詞+關係代詞(whom/which)引導
The man to whom you’re talking is my friend.
I need a pen with which I can write a letter.
=I need a piece of paper on which I can write a letter.
介詞的選用可根據從句中的`相關片語確定，該介詞通常可以放在關係代詞之前，也可放在從句之尾。例如：
The man (who/whom/that) I talked about at the meeting is from Beijing University.
=The man about whom I talked at the meeting is from Beijing University.
The palace (which/that) I often pay a visit to was built in the 17th century.
=The palace to which I often pay a visit was built in the 17th century.
﹙2﹚非限定性定語從句(主句和定語從句之間用逗號隔開)。
① 直接由引導詞引導定語從句。
② 由介詞+關係代詞(whom/which)引導。
I live in a house far away from the city, in front of which is a big tree.
There is an apple tree standing at the gate, on which are many apples.
This is the man to whom I gave the book.
③ 由“代詞/名詞+of+whom/which”或“of which/ whom +名詞/代詞”(先行詞指
人用whom,指物用which)引導。One, some, any, none, all, both, several, many, most, neither, either等詞、數詞、分數或百分比與of whom或of which連用。
He has five children, two of whom are abroad.
(比較：He has five children, and two of them are abroad.)
We have three books, none of which is/are interesting.
(比較：We have three books, but none of them is/are interesting.)
除why和that不能引導非限定性定語從句外，其餘引導詞都可以，用法同限定性定語從句一樣。但要注意以下區別。
1.在形式上非限定性定語從句與主句有逗號隔開。
2.非限定性定語從句的作用：它只是補充說明先行詞的情況，翻譯時可譯成兩個句子。
The engineer, whose leg was badly hurt, was quickly sent to hospital.
(那位工程師被很快送往醫院，其腿部受了重傷)
The engineer whose leg was badly hurt was quickly sent to hospital.
(那位腿部受了重傷的工程師被很快送往醫院)
3.在非限定性定語從句中，任何引導詞都不能省略(包括引導詞在此定語從句中充當賓語在內)。指人做主語時只能用who, 做賓語時用whom;
指物做主語，賓語都用which; 關係副詞用when或where,也不能省略。
The man, ______ is sitting on the chair, is my father.
The woman, _______ I met yesterday, is my English teacher.
The city, _______ is far away, is very beautiful.
He went to America, ______ his parents live.
He joined the Army yesterday, ______ I left, too.
e引導非限定性定語從句：
The house, whose window faces south, is mine.
=The house, the window of which faces south, is mine.
=The house, of which the window faces south, is mine.
二。定語從句中關係代詞和關係副詞的基本用法。
指人是主格在定語從句中代替先行詞，又作定語從句的主語，不能省略。
Do you know the gentleman who/that is sitting there?
指人是賓格，在定語從句中代替先行詞，又作定語從句的賓語(動賓或介賓)。
① 當作動賓(動詞後接賓語)時，關係代詞可省略。
Do you know the gentleman (whom/who/that) we met just now?
② 當作介賓(介詞後接賓語)時：
介詞不提前時，關係代詞可省略;
介詞提前時，關係代詞不可省，即介詞+whom(指人時介詞後的關係代詞只能用whom)。
The man (whom/who/that) I spoke with is my teacher.
The man with whom I spoke is my teacher.
※注：固定的動詞短語(動詞+介詞)如look for, take care of等不能把動詞與介詞拆開，既介詞不能提至引導詞前。
She is the right girl (who/whom/that) we are looking for.
e: 指人或物，是所有格“…的”形式。Whose+n.一起在定語從句中充當主語、賓語(動賓或介賓)即先行詞的什麼東西怎樣了，whose不能省略。Whose+n. = the +n. + of which/whom= of which/ whom+ the =n.
I didn’t find the desk whose leg was broken. (主語)
He is the student whose pencil I broke yesterday. (動賓)
The boss in whose company I work is very kind. (介賓)
h/that 指物，指代先行詞且在定語從句中作主語或賓語(動賓或介賓)。
① 當作動賓時，關係代詞可省略。
② 當作介賓時：
介詞不提前時，關係代詞可省略;
介詞提前時，關係代詞不可省，即介詞+which(指物時介詞後的關係代詞只能用which)。
The house which/that was destroyed in the earthquake is weak.
The pen (which/that) you found yesterday is mine.
The games (that/which) the young men competed in were difficult.
The games in which the young men competed were difficult.
※注：介詞+關係代詞即介詞+whom/which(先行詞指人用whom,指物用which)。
※指人或物，在定語從句中可作主語，賓語，表語或狀語，不能省略。主要用於 “the same …as…;such …as…;so …as…;as … as…;as follows”固定結構中，形式固定此時的引導限定性定語從句。要用as代替who(m), which, 或that引導定語從句：
Such people as knew Hill thought he was honest.
Such people as Hill knew thought he was honest.
My hometown is no longer the same as it was.
Here is so big a stone as no one can lift.
The child knows as much as grow-ups (know).
I’d like to have the same books as are used in your school.
He is not such a person as I expected.
He will marry as pretty a girl as he can find.
※注：which和as可引導非限定性定語從句：可以指代主句中的一部分或整個句子的內容，which和as都可以指代主句中的一部分或整個句子的內容，有時可以互換。因此，當as/which指代前面的整個句子，或前句中的部分內容作定語從句的主語時，謂語用單數。
Our team lost the game, as/which was reported in the newspaper.
She was terrified, as/which I could see from her eyes.
He married her, as/which was natural.
區別：
①as引導的非限制性定語從句可以放在主句前面、插在主句中間或放在主句末尾;而which引導的非限制性定語從句只能放在主句後面。
He married her, as/which was natural.
=As was natural, he married her.
Mark Twin is a great writer, which/as is known to all.
=As is known to all, Mark Twin is a great writer.
②as引導的從句有“正如”、“正像”之意，而which則無此意。常用句型有：
as we all know, as is known to all, as everybody can see, as is expected, As is known/ said/ reported/ told/ we all know等。如：
As we all know, paper was first made in China.
To shut your eyes to facts, as many of you do, is foolish.
③主句和從句有因果關係時，用which.
Our class has won the football match, which made us very happy.
Bamboos are hollow, which makes them very light.
④從句含否定意義時常用which.
She didn’t pass the exam, which we couldn’t expect.
She didn’t pass the exam, as we expected.
關係副詞：指時間。在定語從句中作時間狀語，不能省略。此時的when還可用介詞+which替換(此時先行詞一定是表時間的名詞)。
I still remember the time when I joined the League.
=I still remember the time on which I joined the League.
=I still remember the time (which/that) I joined the League on.
e關係副詞：指地點。在定語從句中作地點狀語，不能省略。此時的when還可用介詞+which替換(此時先行詞一定是表地點的名詞)。
I still remember the school where I joined the League.
=I still remember the school in which I joined the League.
=I still remember the school (which/that) I joined the League in.
※注：對關係副詞when, where的認識。
①. 先行詞是時間的名詞，並非都用關係副詞when引導定語從句。
I’ll never forget the time (which/that) I spent in Beijing.
②. 先行詞是地點的名詞，並非都用關係副詞where引導定語從句。
This is the factory (which/that) he visited yesterday.
③. 當句型為It/This/That is(was) the first(second…last) time引起的句子時用that連線其後的句子。此時的time是次數，不是時間。
It/This is the first time that we travel.
It/This is the last time that I shall give you a lesson.
8. why指原因，在定語從句中作原因狀語，先行詞通常為reason,不能省略。且why引導的定語從句只能是限定性定語從句。Why= for which
I don’t know the reason why he was late yesterday.
The reason why(for which) he was late is that he missed the bus.
※注：當先行詞為reason時，關係副詞並非都用why.
This is the reason (that/ which) he gave/ explained to us.
