英語四級考試的過程中，定語從句在聽力、閱讀和翻譯中經(jīng)常出現(xiàn)，是需要重點(diǎn)把握的語法點(diǎn)之一。下面是小編給大家分享的相關(guān)內(nèi)容，大家可以作為了解。

一、定語從句的種類

定語從句的種類有兩種：一種是限定性定語從句(Restrictive Attributive Clause);另一種是非限制性定語從句(Non-Restrictive Attributive Clause)。

1)、限定性定語從句使修飾的詞，代表一個(gè)、一些或一類特定的人或物。這種定語從句和被修飾的詞構(gòu)成了一個(gè)完整的意思，定語從句不能隨便去掉，否則剩下的部分就會失去意義、意思不完整、不能說明問題、甚至?xí)@得莫名其妙，不知所云而不能成立。主句和從句一般翻譯成一句話。

例如：想去的人請?jiān)谶@里簽名。

(如果去掉定語從句，該句的意思便不清楚了。) 你可以拿任何你喜歡的東西。

2)、非限制性定語從句是對所修飾的詞作進(jìn)一步說明，去掉之后，其他部分意思仍然清楚，非限制性定語從句需要用逗號與主句隔開。主句和從句一般翻譯成兩句話。例如： 那是很重要的(考試)。

在把握定語從句的時(shí)候大家要注意以下幾點(diǎn)：

1. 定語從句的作用主要是用來修飾先行詞;

2. 定語從句和主句之間需要有關(guān)系詞來進(jìn)行連接;

3. 關(guān)系詞在從句中代替先行詞，并且充當(dāng)一定的成分。根據(jù)關(guān)系詞在從句中成分的不同，關(guān)系詞是有所不同的。

二、常見關(guān)系代詞

關(guān)系副詞why主要用于修飾表示原因的名詞(主要是the reason)，同時(shí)它在定語從句中用作原因狀語。如：

We don’t know the reason why he didn’t show up. 我們不知道他為什么沒有來。

關(guān)系副詞when主要用于修飾表示時(shí)間的名詞，同時(shí)它在定語從句中用作時(shí)間狀語。如：

There comes a time when you have to make a choice. 你必須作出抉擇的時(shí)候到了。

關(guān)系副詞where主要用于修飾表示地點(diǎn)的名詞，同時(shí)它在定語從句中用作地點(diǎn)狀語。

如：This is the village where he was born. 這就是他出生的村子。

關(guān)系代詞: whom”作賓語指人，"who"和“that”既可作主語又可作賓語(作主語不可以省略)，可以指人也可以指物。在從句中所起作用如下： 定語從句

(1)Is he the man who/that wants to see you? 他是那個(gè)想見你的男人嗎?(who/that在從句中作主語)

(2)He is the man whom/ that I saw yesterday. 他就是我昨天見的那個(gè)人。(whom/that在從句中作賓語)

which that用來指物

非限制性定語從句

非限制性定語從句起補(bǔ)充說明作用，缺少也不會影響全句的理解。在非限制性定語從句的前面往往有逗號隔開，如The house,which I bought last year,has a lovely garden.　我去年買的的房子帶著個(gè)漂亮的花園。

as, which 非限定性定語從句

as 和which在引導(dǎo)非限制性定語從句時(shí)，這兩個(gè)關(guān)系代詞都指主句所表達(dá)的整個(gè)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(diǎn)：

(1) as 引導(dǎo)的定語從句可置于句首，而which不可。

(2) as 代表前面的整個(gè)主句并在從句中作主語時(shí)，從句中的謂語必須是系動(dòng)詞;若為行為動(dòng)詞，則從句中的關(guān)系代詞只能用which.。

在本題中，prevent由于是行為動(dòng)詞，所以正確選項(xiàng)應(yīng)為B。

As 的用法

例1. the same… as;such…as 中的as 是一種固定結(jié)構(gòu), 和……一樣……。

I have got into the same trouble as he (has).

例2. as可引導(dǎo)非限制性從句，常帶有'正如'。

As we know, smoking is harmful to one's health.

As is know, smoking is harmful to one's health.

As是關(guān)系代詞。例1中的as作know的賓語;例2中，它充當(dāng)從句的主語，謂語動(dòng)詞know要用被動(dòng)式。

三、難點(diǎn)分析

(一)限制性定語從句只能用that 的幾種情況

1.當(dāng)先行詞是anything, everything, nothing (something 除外), few, all, none, little, some 等代詞時(shí)，或者是由every, any, all, some, no, little, few, much 等修飾時(shí)

(1) Have you taken down everything that Mr. Li has said?

(2) There seems to be nothing that seems impossible for him in the world.

(3) All that can be done has been done.

(4) There is little that I can do for you.

注意：當(dāng)先行詞指人時(shí)，偶爾也可以用who

(4) Any man that/.who has a sense of duty won't do such a thing.

2. 當(dāng)先行詞被序數(shù)詞修飾

(1) The first place that they visited in London was the Big Ben.

3. 當(dāng)先行詞被形容詞高級修飾時(shí)

(1) This is the best film that I have seen.

4. 當(dāng)形容詞被the very, the only修飾時(shí)

(1) This is the very dictionary that I want to buy,

(2) After the fire in his house, the old car is the only thing that he owned.

(3) Wang Hua is the only person in our school who will attend the meeting

5. 當(dāng)先行詞前面有who, which等疑問代詞時(shí)

(1) Who is the man that is standing there?

(2) Which is the T-shirt that fits me most?

6. 當(dāng)先行詞既有人，也有動(dòng)物或者物體時(shí)

(1) Can you remember the scientist and his theory that we have learned?

四、定語從句練習(xí)：

1、It was in that house he used to live the secret meeting was held.

;where ;that ;where ;that

2、The foreign guests, were scientists, were warmly welcomed at the airport.

of them of whom of that of those

3、That’s not the book you can find the exact answer.

4、The building over there is a library, is a department store.

of which

the west of it the west of that

5、He was the very one of the students who praised at the class meeting.

1、D 2、B 3、D 4、B 5、A

6、We should learn from those are ready to help others.

7、I have two brothers, are doctors.

of them of who of whom of they

8、 everybody knows, China has the largest population in the world.

A.Which B.That C.As D.The thing

9、Everything can be done should be done.

10、This is the house you saw the other day.

which that

6、A 7、C 8、C 9、B10、A

以上就是英語四級語法知識，希望可以給大家在備考的過程中帶來幫助。