一、弄清关系代词所指及其在定语从句中所充当的句子成分。

1.先行词指物时，用关系代词that/which在从句中作主语或宾语。如:

He bought a coat that/which cost little.

他买了一件便宜上衣。(作主语)

The car which / that he bought yesterday is a secondhand one.

他昨天买的车是个二手货。(作宾语)

2.先行词指人时，用关系代词that/who在从句中作主语或宾语(在口语中，代替whom)。如:

The man who / that gave a speech on TV is the president.

昨天在电视上演讲的人是总统。(作主语)

This is the strange man that/who/whom I met yesterday.

这就是我昨天碰到的那个怪人。(作宾语)

3. whose在从句中作定语，既可指人，作“某(些)人的”解;也可指物，作“某(些)物的”解。如:

This is the little girl whose parents were killed in the great earthquake.

这就是在那次大地震中失去双亲的那个小姑娘。

We live in a house whose windows open to the south.

我们居住在一所窗户朝南的房子里。

理清上述关系还能帮助我们判断定语从句谓语动词的单复数。又如:

He is one of the students who work hard.

他是学习努力的学生之一。(who指先行词the students)

He is the only one of the students who goes abroad.他是学生中唯一出国的。(who指先行词the only one)

二、记清多用关系代词that的几种情况。

1. 先行词为all， everything， nothing， something， anything， little， few， much等不定代词时。如:

There is little that I can use.

几乎没有什么我能用的了。

2. 先行词被all， each， few， much， every， no， some， any等不定代词修饰时。如:

All the books that you need are here.

你所需要的书都在这儿。

3. 先行词被序数词或形容词最高级修饰时。如:

This is the first composition that he has written in English.

这是他用英语写的第一篇作文。

4. 先行词既有人又有物时。如:

He talked about the teachers and schools that he had visited.

他谈到了他曾拜访过的老师和学校。

5. 主句是以who或which开头的疑问句时。如:

Who is the man that is speaking over there?

在那里说话的人是谁?

6. 先行词被the only，the very， the last等修饰时。如:

This is the very gun that I am looking for.

这正是我在找的枪。

7. 关系代词在从句中作表语时。如:

He is not the young man that he was thirty years ago.

他已不是三十年前的那个年轻人了。