定語從句在句中起到形容詞的作用，是高考熱點(diǎn)。學(xué)生對(duì)which和that的使用經(jīng)常混淆。下面把定語從句中關(guān)系詞使用的特殊情況進(jìn)行歸納。

限制性定語從句

1. 當(dāng)先行詞在主句中作表語，而且關(guān)系代詞也在從句中作表語時(shí)，關(guān)系代詞常常用that。

Lianyungang is no longer the city that it was to be.

2. whose 既可以指人，也可以指物，表示所屬關(guān)系，不可省略。whose +名詞這種結(jié)構(gòu)還可以用the +名詞 of which （whose） 來替換，也可以用 of which （whose） 來替換。

This is the new machine whose parts are too small to be seen.

（這里的whose parts = the parts of which = of which the parts）

There comes the scientist whose achievements are well-known.

（其中的whose achievements = the achievements of whom = of whom the achievements）

3. 介詞+關(guān)系代詞which /whom

（1） 當(dāng)介詞放在關(guān)系代詞前面時(shí)，關(guān)系代詞只能用which（指物）或whom（指人），而且關(guān)系代詞不能省略。

Have you found the pen with which you wrote the note？

In the dark street， there wasnt a single person to whom she could turn for help.

（2） 介詞+ which /whom +不定式結(jié)構(gòu)

The wealthy man has a large house in which to live.

4. 當(dāng)先行詞被such修飾，關(guān)系代詞只用as。

They have found such materials as are used in their workshop.（先行詞materials被such修飾，關(guān)系代詞只用as，且as在定語從句中作主語。）

The house was sold at such a high price as people expected.（先行詞price被such修飾，關(guān)系詞只用as，且as在定語從句中作賓語。）

比較下面的一組句子：

The teacher gave us such a difficult problem as no one can solve.（定語從句）

The teacher gave us such a difficult problem that no one can solve it.（狀語從句）

5. the same as 與the same that 含義不同

This is the same magazine as I bought yesterday. 這本雜質(zhì)跟我昨天買的一樣。

This is the same magazine that I bought yesterday. 這就是我昨天買的那本雜志。（同一本）

6. 當(dāng)way（表“方式、方法”）作先行詞時(shí)，如果在定語從句中作主語或作賓語，關(guān)系代詞用that /which，而當(dāng)它在從句中作狀語時(shí)，關(guān)系代詞可用that /in which 或不填。

I like the way （that /which） he used in his work.（作used賓語）

I dont like the way（that/in which /不填）he treats his parents.

7. 當(dāng)reason作先行詞時(shí)，先行詞在句中作狀語時(shí)，關(guān)系詞是why（for which）；如果先行詞reason在句中作為主語或者賓語，仍然用which或that。

Can you believe the reason that /which he gave at the meeting？

Do you know the reason why （= for which） he was absent？

8. 英語中有幾個(gè)詞，像point， case， stage， situation， degree作先行詞，大體表示“地步，境地，情況”，并且它在定語從句中既不作主語，也不作賓語的情況下，關(guān)系詞常用where。

He has reached a point where he has to make a decision himself. 而occasion 則常常與when連用。

The occasion arises when he can go abroad to study.

非限制性定語從句

1. 在非限制性定語從句中，即使先行詞在定語從句中作賓語，關(guān)系詞也不能省略。

He has a close friend， who works as a doctor.

His home is near the museum， which we visited last week.

2. 在非限制性定語從句中，當(dāng)表示先行詞的一部分時(shí)，也可用名詞/代詞+ of + which （whom） 來表示。

I have some friends， several of whom are business men.

或者I have some friends， of whom several are business men.

There are about 140 kinds of snakes in Australia， most of which are not dangerous.

或者There are about 140 kinds of snakes in Australia， of which most are not dangerous.

3. 關(guān)系代詞as、which引導(dǎo)非限制性定語從句的區(qū)別

（1） as和which都可以替代主句的整個(gè)內(nèi)容（which還可以替代一個(gè)詞），as引導(dǎo)的非限制性定語從句即可放在主句前，又可在主句后，有時(shí)還可以插入主句中，而which引導(dǎo)的非限制性定語從句一般置于主句之后。

By serving others， a person focus on someone other than himself or herself， which can be very eye-opening and rewording.

A. who B. which C. what D. that

Many animals sleep a lot when young， but sleep much less when they get older， just as is the case with human being.

A. as B. which C. what D. it

（2） as引導(dǎo)的非限制性定語從句的內(nèi)容與主句往往是相符的，一致的，常常是肯定的，所以as常與以下關(guān)系詞連用：as is often the case， as is said， as is reported， as is mentioned above， as is known等，而which引導(dǎo)的非限制性定語從句與主句內(nèi)容常常是不相符的，不一致的，否定的。

As you know， the earth travels around the sun.

He came late， which is unexpected.

（3） 當(dāng)非限制性定語從句句型為賓語補(bǔ)足語結(jié)構(gòu)時(shí)，常常用which引導(dǎo)。

He was late， which made his teacher surprised.