（1）定语从句有限制性和非限制性两种。限制性定语从句是先行词不可缺少的部分，去掉它主句意思往往不明确；非限制性定语从句是先行词的附加说明，去掉了也不会影响主句的意思，它与主句之间通常用逗号分开。例如：·This isthe house which we bought last month.这是我们上个月买的那幢房子。（限制性）·Thehouse, which we bought last month, is very nice.这幢房子很漂亮，是我们上个月买的。（非限制性）
（2） 当先行词是专有名词或物主代词和指示代词所修饰时，其后的定语从句通常是非限制性的。例如：·CharlesSmith, who was my former teacher, retired last year.查理·史密斯去年退休了，他曾经是我的老师。·Myhouse, which I bought last year, has got a lovely garden.我去年买的那幢房子带着个漂亮的花园。· Thisnovel, which I have read three times, is very touching.这本小说很动人，我已经读了三遍。
（3） 非限制性定语从句还能将整个主句作为先行词, 对其进行修饰, 这时从句谓语动词要用第三人称单数。例如：·Heseems not to have grasped what I meant, which greatly upsets me.他似乎没抓住我的意思，这使我心烦。·Liquidwater changes to vapor, which is called evaporation.液态水变为蒸汽，这就叫做蒸发。说明：关系代词that和关系副词why不能引导非限制性定语从句。
(4) 定语从句有限制性和非限制性两种。限制性定语从句是先行词不可缺少的部分，去掉它主句意思往往不明确；非限制性定语从句是先行词的附加说明，去掉了也不会影响主句的意思，它与主句之间通常用逗号分开，例如：
This is the house that we bought last month. 这是我们上个月买的那幢房子。（限制性）
The house, which we bought last month, is very nice.这幢房子很漂亮，是我们上个月买的。（非限制性）
(5) 当先行词是专有名词或物主代词和指示代词所修饰时，其后的定语从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，他曾经是我的老师。
My house, which I bought last year, has got a lovely garden. 我去年买的的那幢房子带着个漂亮的花园。
This novel, which I have read three times, is very touching. 这本小说很动人，我已经读了三遍。
(6) 非限制性定语从句还能将整个主句作为先行词, 对其进行修饰, 这时从句谓语动词要用第三人称单数，例如：
He seems not to have grasped what I meant, which greatly upsets me. 他似乎没抓住我的意思，这使我心烦。
Liquid water changes to vapor, which is called evaporation. 液态水变为蒸汽，这就叫做蒸发。
说明：关系代词that和关系副词why不能引导非限制性定语从句。
练习题：
1.I know the boy ____________ you gave the book____________.
；to h；to whom；to ；to him
in is the very place ____________ I’m anxious to pay a visit.
h which which
you been to Hangzhou____________ West Lake is the most beautiful in our country？
e h e
4.I know the student ____________ you borrowed the pen.
whom which
are players from Japan，____________ are our old friends.
e
arrived at the farmhouse in front of ____________ sat a small boy.
place h
is the day ____________ I’ll never forget.
A./ which which
letter is from my sister，____________ is working in Beijing.
h
9.I bought a book，____________ I can’t remember now.
title e title title of it title of that
10.I want to use the same dictionary ____________ was used yesterday.
h
is good at English，____________ we all know.
12.I’ll never forget the days ________ we spent together in the countryside.
which h which
is the best film ____________ I have ever seen.
h that
is the only one of the students ____________ from Shanghai.
is are are come
Scott is one of the foreign experts who ____________ in China.
s working working been working
16.I，who ____________ in America，feel proud of being a Chinese.
B./ g
’ll never forget the people and the place ________ she visited in Beijing last year.
h e
you know the reason ____________ he was late？
what h which
1~5 ADABD 6~10 CACBD 11~18 BCAAC CAC
用关系代词填空.(答案可能不唯一)（that, which, who, whom, whose）
1. These books _____________ you lent me were very useful.
2. The storybook ____________ I have just read cannot be easily forgotten.
3. A dictionary is a book _____________ gives the meaning to the word.
4. Is there anyone ____________ family is in Beijing?
5. This is the best film ________ has been shown this year.