所謂定語從句，就是在複合句中起定語作用以修飾主句中的名詞或代詞的從句。下面是小編為大家收集整理的定語從句英語語法相關內容，歡迎閱讀。
一、關係代詞引導的定語從句
關係代詞所代替的先行詞是人或物的名詞或代詞，並在句中充當主語、賓語、定語等成分。關係代詞在定語從句中作主語時，從句謂語動詞的人稱和數要和先行詞保持一致。
1who, whom, that
這些詞代替的先行詞是人的名詞或代詞，在從句中作主語和賓語。
例如：Is he the man who/that wants to see you? 他就是你想見的人嗎?(who/that在從句中作主語)
He is the man whom/ that I saw yesterday. 他就是我昨天見的那個人。(whom/that在從句中作賓語)
2whose 用來指人或物，(只用作定語, 若指物，它還可以同of which互換)。
例如：They rushed over to help the man whose car had broken down. 那人車壞了，大家都跑過去幫忙。
Please pass me the book whose (of which) cover is green. 請遞給我那本綠皮的書。
3which, that所代替的先行詞是事物的名詞或代詞，在從句中可作主語、賓語等。
例如：A prosperity which / that had never been seen before appears in the countryside.
農村出現了前所未有的繁榮。(which / that在句中作賓語)
The package (which / that)you are carrying is about to come unwrapped. 你拿的包快散了。(which / that在句中作賓語)
二、關係副詞引導的定語從句
關係副詞可代替的先行詞是時間、地點或理由的名詞，在從句中作狀語。
1關係副詞when, where, why的含義相當於"介詞+ which"結構，因此常常和"介詞+ which"結構交替使用。
例如：I will never forget the day when I met her. 我將永遠不會忘記我見到她的那一天
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?
4that代替關係副詞，可以用於表示時間、地點、方式、理由的名詞後取代when, where, why和"介詞+ which"引導的定語從句，在口語中that常被省略。
例如：His father died the year (that / when / in which) he was born. 他父親在他出生那年逝世了。
He is unlikely to find the place (that / where / in which) he lived forty years ago. 他不大可能找到他四十年前居住過的地方。
三、判斷關係代詞與關係副詞
關係詞的選擇依據在從句中所做的成分，先行詞在從句中做主、定、賓語時，選擇關係代詞(who, whom, that, which, whose); 先行詞在從句中做狀語時，應選擇關係副詞 ( where 地點狀語，when 時間狀語，why 原因狀語) 。
1用關係代詞，還是關係副詞完全取決於從句中的謂語動詞。及物動詞後面無賓語，就必須要求用關係代詞;而不及物動詞則要求用關係副詞。
如：This is the mountain village where I stayed last year. 這是我去年呆過的山村。
I'll never forget the days when I worked together with you.我永遠不會忘記與你共事的日子。
判斷改錯：
(錯) This is the mountain village where I visited last year.
(錯) I will never forget the days when I spent in the countryside.
(對) This is the mountain village (which) I visited last year.
(對) I'll never forget the days (which) I spent in the countryside.
習慣上總把表地點或時間的名詞與關係副詞 where, when聯絡在一起。此兩題錯在關係詞的誤用上。
2準確判斷先行詞在定語從句中的成分(主、謂、賓、定、狀)，也能正確選擇出關系代詞/關係副詞。
例1. Is this museum ___ you visited a few days age?
A. where B. that C. on which D. the one
例2. Is this the museum ____ the exhibition was held.
A. where B. that C. on which D. the one
答案：例1 D，例2 A
例1變為肯定句： This museum is ___ you visited a few days ago.
例2變為肯定句： This is the museum ___ the exhibition was held.
在句1中，所缺部分為賓語，而where, that, on which都不能起到賓語的作用，只有the one既做了主句的表語，又可做從句的賓語，可以省略關係代詞，所以應選D。
而句2中, 主、謂、賓俱全，從句部分為句子的狀語表地點，既可用副詞where，又因 in the museum片語，可用介詞in + which 引導地點狀語。而此題中，介詞on 用的不對，所以選A。
四、限制性和非限制性定語從句
1定語從句有限制性和非限制性兩種。限制性定語從句是先行詞不可缺少的部分，去掉它主句意思往往不明確;非限制性定語從句是先行詞的附加說明，去掉了也不會影響主句的意思，它與主句之間通常用逗號分開。
例如：This is the house which we bought last month. 這是我們上個月買的那幢房子。(限制性)
The house, which we bought last month, is very nice.這幢房子很漂亮，是我們上個月買的。(非限制性)
2當先行詞是專有名詞或物主代詞和指示代詞所修飾時，其後的定語從句通常是非限制性的。
例如：Charles Smith, who was my former teacher, retired last year. 查理?史密斯去年退休了，他曾經是我的老師。
My house, which I bought last year, has got a lovely garden. 我去年買的的那幢房子帶著個漂亮的花園。
This novel, which I have read three times, is very touching. 這本小說很動人，我已經讀了三遍。
3非限制性定語從句還能將整個主句作為先行詞, 對其進行修飾, 這時從句謂語動詞要用第三人稱單數。
例如：He seems not to have grasped what I meant, which greatly upsets me. 他似乎沒抓住我的意思，這使我心煩。
Liquid water changes to vapor, which is called evaporation. 液態水變為蒸汽，這就叫做蒸發。
說明：關係代詞that和關係副詞why不能引導非限制性定語從句。
五、介詞+關係詞
1介詞後面的關係詞不能省略。
2that前不能有介詞
3某些在從句中充當時間，地點或原因狀語的"介詞+關係詞"結構可以同關係副詞when 和where 互換。
例如：This is the house in which I lived two years ago. 這是我兩年前住過的房子。
This is the house where I lived two years ago.
Do you remember the day on which you joined our club? 還記得你加入我們俱樂部的那一天嗎?
Do you remember the day when you joined our club?
六、as, which 非限定性定語從句
由as, which 引導的非限定性定語從句，as和which可代整個主句，相當於and this或and that。As一般放在句首，which在句中。例如：
As we know, smoking is harmful to one's health. 如我們所知，吸菸有害健康。
The sun heats the earth, which is very important to us. 太陽使地球暖起來，這對我們人類很重要。
典型例題:
1)Alice received an invitation from her boss, ___came as a surprise.
A. it B. that C. which D. he
答案C. 此為非限定性從句，不能用 that修飾，而用which.，it 和he 都使後
句成為句子，兩個獨立的句子不能單以逗號連線。況且選he句意不通。
2)The weather turned out to be very good, ___ was more than we could expect.
A. what B. which C. that D. it
答案B。which可代替句子，用於非限定性定語從句，而what不可。That 不能用於非限定性定語從句，it不為連詞，使由逗號連線的兩個句子並在一起在英語語法上行不通。
3)It rained hard yesterday, ____ prevented me from going to the park..
A. that B. which C. as D. it
答案B. as 和which在引導非限制性定語從句時，這兩個關係代詞都指主句所表達的整個意思，且在定語從句中都可以作主語和賓語。但不同之處主要有兩點：
(1)as 引導的定語從句可置於句首，而which不可。
(2) as 代表前面的整個主句並在從句中作主語時，從句中的謂語必須是系動詞;若為行為動詞，則從句中的關係代詞只能用which.。在本題中，prevent由於是行為動詞，所以正確選項應為B。
as 的用法:
例1. the same…as;such…as 中的as 是一種固定結構, 和……一樣……。例如：
I have got into the same trouble as he (has). 我碰到了跟他一樣的'麻煩。
例2. as可引導非限制性從句，常帶有'正如'。例如：
As we know, smoking is harmful to one's health. 如我們所知，吸菸有害健康。
As is known, smoking is harmful to one's health.
As是關係代詞。例1中的as作know的賓語;例2中，它充當從句的主語，謂語動詞know要用被動式。
七、先行詞和關係詞二合一
1) Whoever spits in public will be punished here. (Whoever 可以用 anyone who 代替)
2) The parents will use what they have to send their son to technical school.(what 可以用all that代替)
八、what/whatever; that/what; who/whoever
1)what = the thing which;whatever = anything.例如：
What you want has been sent here. 你要的動詞都送來了。
Whatever you want makes no difference to me. 不管你要什麼，跟我沒什麼關係。
2) who= the person that whoever= anyone who。例如：
(錯)Who breaks the law will be punished.
(錯)Whoever robbed the bank is not clear.
(對)Whoever breaks the law will be punished. 王子犯法，與庶民同罪。
(對)Who robbed the bank is not clear. 誰搶了銀行還不清楚。
3) that 和 what
當that引導定語從句時，通常用作關係代詞，而引導名詞性從句時，是個不充當
任何成分的連線詞。賓語從句和表語從句中的that常可省略。What只能引導名詞性從句，用作連線代詞，作從句的具體成分，且不能省略。例如：
I think(that)you will like the stamps. 我想你會喜歡這些郵票的。
What we need is more practice. 我們需要的是更多的實踐。
九、關係代詞that 的用法
1不用that的情況
a) 引導非限定性定語從句時。例如：
(錯)The tree, that is four hundred years old, is very famous here.
b) 介詞後不能用。例如：
We depend on the land from which we get our food. 我們依賴土地獲得食物。
We depend on the land that/which we get our food from.
2用that情況
(a) which與that指物時可互相代替，但that比which更常見，尤其在口語中。但要注意that可用來指人，而which則不能指人。
只能用that不能用which引導的定語從句：
①定語從句所修飾的詞，同時又被形容詞最高階修飾時，定語從句只能用that引導;
This is the most interesting story (that) I have ever heard.
②定語從句所修飾的詞，同時又被序數詞修飾時，定語從句只能用that引導;
The children like the second Lesson that is about “The Football March”.
③定語從句所修飾的詞，同時又被the only，the very或the same修飾時，
定語從句只能用that引導;
1) It is the only word (that) I know in the passage.
2) This is the same bicycle (that) I lost.
④定語從句修飾的詞同時又被不定代詞，如：all，any，no，every，little，many或much等修飾時，定語從句只能用that引導;
Here is all the money (that) I have.
⑤定語從句修飾詞為everything，something，anything，nothing，all，none，much，little，few等不定代詞時，定語從句只能用that引導。但something前有the時，定語從句可由which引出。
Here is something (that) I will tell you.
I want everything (that) I want.
⑥定語從句修飾的詞中同時含有“人”和“物”的名詞時，定語從句只能用that引導：
I can remember well the persons and some picture (that) I see in the room.
⑦定語從句修飾的詞為one, ones時，定語從句用that引導：
Is it the one (that) you want?
⑧當主句的主語是疑問詞 who或 which來提問時，為了避免重複，用that引導定語從句：]
Who is the girl that won the first place?
(b) who指人，that除指人外也指物，在從句中作主語或賓語。作賓語可省略，作主語不能省略。
1) The girl who often helps me with my English is from England. (作主語，不可省略)
2) The teacher who spoke at the meeting just now is having a rest in his office. (作主語，不可省略)
3) The boy (who/ that) I like isn’t here now. (作賓語，可省略)
注 意:who與that指人時可互相代替，但下列情況只能用who不能用that引導的定語從句：
① 先行詞是one，ones，anyone時，定語從句只能用who引導;
② 先行詞為those時，定語從句只能用who引導;
③ There be句型開頭。
另 注：(1) whom指人，為who的賓格形式,在句中只作賓語，其前沒有介詞時，也可用who替換使用，也可省略，如：
Who is the teacher (that/ who/ whom) Yanzhen is talking to? (作賓語，可省略)
Who is the teacher to whom Yanzhen is talking? (作賓語，介詞to提到whom前，whom再此不可省略)
(2) whose 指人，也可指物，在從句中作定語，不可省略。如：
The building whose windows face to the south is our school. (作定語，不可省略)
注意：1)在關係代詞that，which，who，whom引導的定語從句中，只有當他們做定語從句的賓語時，才可以省略。
2) 關係代詞在定語從句中做主語，動詞單複數由其前的名詞或代詞決定。
He who doesn’t study hard won’t pass the exam.
3) 因為關係代詞或關係副詞在定語從句中已充當一個成分，該從句中不能出現與它重複的成分。
That is the only movie (that)I’d like to see. (對)
That is the only movie (that)I’d like to see it. (錯)
