限制性分句和非限制性分句
限制性分句的类型
限制性关系分句主要是对先行词起修饰作用。它可以用于修饰、限制主句中主语、宾语、介词宾语或表语。
修饰主句的主语
There are many people who want to see you.
The book which I borrowed from the library tells about bionics.
修饰主句的宾语
I have visited a plant which produces chemical fertilizer.
Do you know the man whom they invited to give a report?
修饰主句的介词宾语
We are interested in the film which tells about the life of the peasants in the mountainous areas.
We are fond of the course professor Smith gives us.
修饰主句中的表语
He is the best man I have cooperated with.
Is that the book you bought last week?

限制性关系分句主要用于以下场合：
1、无连词关系分句一般都是限制性关系分句
The family he lived with adored him very much.
This is the knife we cut bread with.
2、先行词前有定冠词(限制性关系分句中先行词前的定冠词the代表特指意义，
非限制性关系分句中，先行词前也有用the的，但一般指上文提到过的人或事)或被最高级形容词修饰
The man you are looking for has left for Beijing.
This is the most difficult exercise I have found in this workbook.
3、先行词被序数词或only等词修饰
The first thing (that) we should do is to work out the plan.
He is always the last person who leaves the workshop.
That was the only method we could use in our experiment then.
4、先行词是不定代词something, anything, someone, anyone, one等时
I cannot tell you anything he told me.
There is someone who wants to see you.
The man I will choose should be the one who works selflessly.
5、those或泛指人称代词作先行词时
Those who agreed to the plan put up their hands.
He who did such a thing could not deserve respect.
6、先行词前有不定冠词或先行词前不用冠词，但先行词又是复数形式时
A woman who can achieve so much is certainly worth respecting.
People who live in this area have begun to live a comfortable life.
Lucy talked about things and events which interested her during her tour to Beijing.
7、关系代词as，that与such the same，as so等连用时
I have never met such a person as you described just now.
Here is so big a stone as no man can lift.
Have you bought the same book as I referred to you?
Will you take with you the same book that I told you?

非限制性分句的类型
1、先行词是主句中的主语
John Smith, who teaches English in an American university, has been invited to be a visiting professor in our university.
Hangzhou, which is famous for its West Lake, will become a city for tourists.
2、先行词是主句中的宾语
She studies English, which is widely spoken in the world.
This note was left by Mr. Hood, who was here a moment ago.
3、先行词是主句中的表语
This is Mr. Robert, who came to China last year.
This is my mother, who works in a hospital.
4、先行词是主句中的状语
She is going to spend the summer holidays in Changsha, where she has some relatives.
He was born in 1949, when China was liberated.
5、先行词是整个主句
He caught up with his class in his studies within such a short period, which pleased the teacher.

非限制性关系分句主要用于以下场合
1、先行词是专有名词，专有名词不需要任何限制和修饰，只需要加以说明或描述，专有名词后的关系分句一般是非限制性的。
Abraham Lincoln, who led the American people in over-throwing the Negro slave system, is considered one of the greatest American presidents.
但当专有名词需要与其它专有名词区别时，可以用于限制性关系分句。
This is the Johnson who compiled the English dictionary.
The West Lake we toured is famous all over the world.
2、先行词是整个句子时，这时的关系分句是非限制性的
He admired Mrs. Brown, which I found strange.
Henry studied extremely hard, which enabled him to pass the entrance examination.
The teacher gave me a lot of help, which was kind of him.
3、独一无二的普通名词作先行词，关系分句一般是非限制性的。
My father, who had been on a visit to America（word语法检查建议此处加逗号） came back to Shanghai the day before yesterday.
His wife, whom you met in my house（word语法检查建议此处加逗号） is a scientist too.
Football, which is a very interesting game（word语法检查建议此处加逗号）is played all over the world.
4、除以上外，有时根据具体句子含义来决定采用限定还是非限定性关系分句表达。