要了解定語從句，我們先得明白定語是啥，如果我給介紹一個人或者描述一樣東西，以介紹一個人爲例，如果我說是個女孩，那麼你頭腦中的對我介紹的人印象清晰麼，應該就一女孩輪廓，但如果我說一個漂亮的，穿着紅色衣服的，站在站臺上的，那麼你對這個人印象是不是逐漸清晰了，這裏漂亮的，紅色的，站在站臺上的便是定語。
我們看看例子先
a pretty girl
a girl in red
a girl standing in the platform
a girl who is standing in the platform is lucy
上例中打彩色部分便都是定語，定語通常是修飾名詞，如果定語是一個詞並且能完整表達一個意思，定語便放在被修飾詞前面，否則就放後面，請觀察pretty是一個詞，便是放前面的，這是你也許會說，a pretty little girl，pretty 和little不是兩個詞，怎麼就放被修飾詞前面了呢，一定要注意，pretty和little都是一個並且是各自能表達完整的意思滴。
上例中彩色部分都是定語，定語可以是一個形容詞(pretty)，可以是介詞短語(in red)，也可以是分詞短語(standing in the platform)，也可以是一個句子(who is standing in the platform)，而當定語從句是一個句子時，這個句子呢，就是定語從句。
由於定語從句是一個句子，毫無疑問滴，必定不可能是一個詞，所以都是放在被修飾詞的.後面，我們還給這個被修飾的詞起了個名字，先行詞，因爲修飾她的句子還在後面，她先出現的。
然後我們在說說這定語從句，在英語中呢有個規定就是一個句子中有且只能有一個謂語，就好比我們人呢只能有一個心臟。(事物是普遍聯繫的定語從句經典例句)，那我們人啥時候可能會有兩個心臟呢?。。。。。對了，有寶寶的時候，男同胞貌似目前不可能哈，那麼句子有個子句的時候便可以有兩個謂語了，這時候我們便需要一個東西來標誌其子句特徵，人類呢是以大肚子，從句便以她的關係代詞。我們例子中的who便是關係代詞，這個關係我們也可以理解成人類的臍帶，將子句和母句聯繫到一起。所以這關係代詞也是緊挨着先行詞的。
所以偶們先要搞清楚啥是定語從句，啥是先行詞，啥是關係代詞。咱再琢磨這定語從句如何用。
is a famous star.
’s that girl in red?
3.A suitcase that doesn’t have handles is useless.
blue suitcase ,which doesn’t have handles, is useless.
注意上面畫線部分有什麼相同的。
都是修飾名詞，對一個名詞進行修飾，補充，讓我們對這個名詞在我們頭腦中都有更清晰的認識。
這類成分就是定語。
觀察最後兩句，充當定語時一個完整句子，我們叫這類叫定語從句。
注意定語從句，that doesn’t have handles，that作代詞+連詞，在從句充當主語，並且連接兩個句子。
我們叫that爲關係代詞。和普通代詞的區別是它還可以連接兩個句子。
被修飾的詞叫先行詞。如最後兩句的suitcase。
Restrictive: A suitcase that doesn't have handles is useless.
Non-Restrictive: The blue suitcase, which doesn't have handles, is useless.
注意這兩個句子。
限定性定語從句和非限定定語從句的區別在哪裏。
前面那句是限制性定語從句，定語從句對先行詞進行修飾，緊挨先行詞，去掉從句句子不完整。
後面那句是非限定定語從句，定語從句對先行詞進行補充說明，先行詞和從句用逗號隔開，去掉句子仍然完整。
對定語從句有大概瞭解後，我們看看關係詞，我們得搞清楚這什麼時候用什麼關係詞，關係詞分關係代詞和關係副詞，關係詞通常在定語從句中充當成分的，當關系詞在句子中作狀語的時候便用關係副詞
引導定語從句的關係詞有關係代詞who, whom, whose, that, which, as和關係副詞when, where, why等。
關係副詞在定語從句中充當副詞，關係代詞中比較難區別是that和which，which 指物，who(whom)指人，that可以指人也可以指物。但有時有些情況只能用that。
觀察下面句子。
is the second article that I have written in English.
is the best film that he has ever seen.
is the very book that I want to read.
4. All that they told me surprised me.
talked about the teachers and schools that they had visited.
6. Who is the girl that was there?
e is a bed in the room that is still vacant.
在上面幾種情況下，關係詞只能用that。
自己總結下吧
1，通常用that的情況
following cases,“that”is often used.
(1)After ordinal number and superlatives.
(2)After the following words:all, only, little, few, much, very, none, last, just, any(thing), every(thing), some(thing),no(thing).
(3)After two or more antecedents,referring to both people and things.
(4)After interrogative pronouns“which”or “who”.
(5) When the main clause begins with “There be”.
2.通常用which的情況
following cases,“which”is always used.
Football,which is a very interesting game,is played all over the world.
This is the house in which he lives.
That pen which he took is mine
(1)After prepositions.
(2)To introduce a Non-restrictive Attributive Clause.
(3)The antecedent is “that”.
練習
將下列兩個單句合併成定語從句
1. The boys are from Class One. The boys are playing football.
2. Mr. Ling is just the boy. I want to see Mr. Ling.
3. There is somebody here. Somebody wants to speak to you.
4. Football is a game. Football is liked by most boys.
5. I will never forget the day. We met there on the day.
6. This is the house. I was born in the house.
7. Do you know the woman? Her son saved the boy's life.
8. The man gone to Guangzhou. You met him in the street yesterday.
9. The book is very interesting. I borrowed it from the library last week.
10. I was looking for a book this morning. I’ve found it now.
T:Now let’s do some at the in the blanks,choosing proper relative pronouns or relative adverbs.
me the reason for__________you were late for class.
is the girl__________is speaking there?
is Mr Smith,__________has some thing interesting to tell you.
computer__________CPU doesn’t work has to be repaired.
kind of computer,__________is well-known,is out of date.
is just the place__________I’ve been longing to visit for years.
mother is an engineer,__________makes him very proud.
old man has four sons,three of__________are doctors.
Suggested answers:
I think“….”should be use the antecedent is“….”and the relative is used as … in the Attributive Clause.
h e h h
