定語從句的基本語法
關係詞不僅起連接作用，而且還代表先行詞並在定語從句中擔任某一句子成分，小編收集了定語從句的基本語法，歡迎閲讀。
有關定語從句的概念
(1)定語從句：就是在複合句裏充當定語的從句，它通常緊靠在所修飾的名詞或代詞後面。
(2)先行詞：就是被定語從句修飾的名詞或代詞。
(3)關係詞：引導定語從句的詞叫關係詞。關係詞有關係代詞who, whom, whose, which和that等;關係副詞有when, where, why等。關係詞不僅起連接作用，而且還代表先行詞並在定語從句中擔任某一句子成分，關係代詞作主語、賓語、定語、表語等，關係副詞作狀語。如：
This is the book that my father bought me yesterday. 這就是我父親昨天幫我買的那本書。
説明：句中修飾the book的that my father bought me yesterday就是定語從句;被定語從句所修飾的the book這是先行詞;代表the book的關係代詞that在定語從句中作bought的直接賓語。
The time when he arrives is not known. 他到達的時間還不知道。
説明：句中when he arrives是定語從句，被定語從句修飾的the time是先行詞，關係副詞when作時間狀語。
關係代詞的一般用法
先行詞是人，在從句中作主語用who，作賓語用whom或who，作定語用whose;先行詞是物，在定語從句中作主語或賓語都用which，作定語用of which或whose均可。在限制性定語從句中which, who, whom都可用that代替。關係代詞作賓語時常被省略。
This is the man who helped me yesterday. 這就是昨天幫助我的那個人。(作主語)
The teacher (who/whom/that) you want to see is coming. 你要見的老師來了。(作see的賓語，可以省略)
I met a boy whose father was a astronaut. 我認識一位男孩，他的父親是宇航員。(作定語)
Here is the coat which/that will be made to you. 這是一件做給你的衣服。(作主語)
This is the factory (which/that) we visited last year.這就是我們去年參觀的那家工廠。(作visited的賓語，可以省略)
He has a book whose cover (=the cover of which) is very beautiful. 他有一本封面非常漂亮的書。
關係副詞的一般用法
關係副詞有when, where, why，在定語從句中作狀語，分別表示時間、地點和原因。when的先行詞通常是time, day, season, age, occasion等時間名詞;where的先行詞通常是place, city, town, village, house, case, situation, scenes等地點或情形名詞;why的先行詞只能是reason。關係副詞when和where有時可用“介詞+which”代替，why可用for which代替。如：
There are occasions when (=on which) one must yield. 任何人都有不得不屈服的時候。
Beijing is the place where (=in which) I was born. 北京是我的.出生地。
Is this the reason why (=for which) he refused our offer? 這就是他拒絕我們幫助他的理由嗎?
注意：先行詞雖然是時間或地點，但若在定語從句中作主語或賓語時，要用關係代詞。
(1)The factory where his father worked has closed. 他父親曾工作的那家工廠關閉了。(作狀語)
比較：The factory which/that was built in 1978 has closed. 1978年建的那家工廠關閉了。(作主語)
(2) I’ll never forget the days when we lived together. 我永遠也忘不了我們一起生活的那些日子。(作狀語)
比較：I’ll never forget the days (that) we spent in Australia. 我永遠也忘不了我們在澳大利亞度過的那些日子。(作及物動詞spent的賓語)
(3) The reason (why) she was ill was that she had eaten bad meat. 她生病的原因是她吃了變質的肉。(作狀語，用關係副詞)
比較：The reason (that) he gave for his absence was obviously fabricated.他所説的缺席理由顯然是編造的。(作gave的賓語，用關係代詞)
習慣上要用that引導的定語從句
(1)當先行詞是指物的all, little, few, much, any, anything, everything, nothing, none, the one時，或先行詞被all, little, few, much, any, every, no等修飾時。
All that can be done has been done. 能做的都已經做了。
He will tell you everything that he heard about it.他將告訴你他所聽到的關於這件事的一切。
There is little work that is fit for you. 沒什麼工作適合你做。
I have eaten all the food that is left. 我把剩下的所有食物都吃了。
(2)先行詞是序數詞或最高級形容詞時，或者先行詞被序數詞(包括last, next)、最高級形容詞及the only, the very 等修飾時。
This is the first film that I have seen since I came here.這是我到這裏後所看的第一場電影。
This is the best that has been used against pollution. 這是用來防止污染的最好辦法。
This is the very book that I am looking for. 這正是我一直在尋找的那本書。
(3)先行詞包括人和物時
They often talk about the people and the things that they are interested in. 他們常常談論那些他們感興趣的人和事。
(4)當主句是以who或which開頭的疑問句時，為了避免重複，多用that引導。如：
Which is the house that caught fire last night? 昨晚失火的是那座房子?
Who is the lady that is playing the piano? 在彈鋼琴的那位小姐是誰?
習慣上不用that引導的定語從句
(1)在非限制性定語從句中，不以能用that引導。
Yesterday I met Mary, who seemed very excided. 昨天我碰到了瑪麗，她顯得非常興奮。
(2)直接在介詞後作賓語時，不能用that引導，要用whom, whose或which，且不能省略。
The house in which we live is not large. 我們住院的房子不大。
I know the young man with whom you live. 我認識和你住在一起的那個年青人。
但當介詞放在從句的末尾時，可以用that替代which, who替代whom，也可以省略關係代詞。如：
The house (which/that) we live in is not large. 我們住院的房子不大。
I know the man (whom/who/that) you live with. 我認識和你住在一起的那個人。
(3)當先行詞是指人的all, any, few, one(s), anyone, everyone, people 等時，多用 who。如：
None so blind as those who won't see. 睜眼不看事實的人眼最瞎。
Anyone who is over sixteen is allowed in. 任何超過十六歲的人都允許進去。
I met someone who said he knew you. 我碰到一個人，他説認識你。
He who has a mind to beat his dog will easily find his stick. (諺)欲加之罪,何患無辭。
(4)當先行詞與關係代詞之間有較複雜的短語或從句隔開時
I was the only person in my office who was invited. 我是我們辦公室裏唯一受到邀請的人。
A new master will come tomorrow who will teach you German. 有位新校長明天來，他將教你們德語。
