定语 从句由关系词（关系代词、关系副词）引导，关系代词、关系副词位于定语从句句首。
定语从句例子先行词
Chinese knots ,which I made by myself with red silk thread and other material, look really beautiful in the shape of diamond.（2013年广西卷）
2. I will organize some campus activities, like “English Evening”, a platform where students can show their English（2013年天津卷）
3.I read the announcement of the summer camp that you have posted on the Internet and I am interested in it. (2012全国卷)
4. In the English corner, I meet many friends, who share the same interest with me. (2012·全国卷Ⅱ)
5. My physics teacher is my role model, whose influence on me had a lot to do with my decision.（2012安徽卷）
6. To avoid such conflicts, we should be kind to one another, which is essential to enjoy a harmonious life.（2012江苏）
7. As we know, books are the source of knowledge. (2012·湖北)
8. Dear friends , please actively take part in after-class activities , which will not only make your school life colorful , but also improve your learning.（2011四川卷）
9. I have taken with me the two books (that) you asked me to return to the City Library. (2009全国I)
reason why we have to grow trees is that they supply us fresh air.
11. I always miss the days when we were on the summer camp last year.
12. It's time to recall those beautiful days we spend together.（2007年湖南卷）
定语从句特定选择
关系词
1、只用that不用which
1）当先行词是序数词或被序数词、最高级，关系词用that。
2）当先行词既有人又有物时，用that。
3）当先行词带有the only,the very,the same,the last,the one等词时，用that。
4）当主句中有who或which时，为避免重复用that。
5）当先行词为something，anything，nothing，none，no，little，much，all等不定代词时用that。
2、只用who不用that
1）如果先行词是those,they,all,persons,people,he,anyone,one时用who
2）当先行词指人并含有较长的后置定语从句或在被分割的定语从句中时。
3、只用which不用that
1）当主句先行词后有介词时，用which。例：This is the one of which I'm speaking。
2）非限定性定语从句，用which。
3) 描述句中一般用which。例：Beijing，which was China's capital for more than 800years。
4）those +复数名词之后，多用which .例：Shopkeeper want to keep a number of those goods which sell best。
5）先行词本身是that时，用which。
定语从句误区提醒
1）当表示时间或地点的名词作先行词时，要判断出它们在从句中作状语还是主语或宾语。作状语时用关系副词，反之用关系代词。
典型例题：I can never forget the day _______ we worked together and the day ______ we spent together.
A. when; which B. which; when C. what; that D. on which; when
答案：A
解析：两个先行词the day都是表示时间的.名词,但第一个空白处要填的关系词在从句中作状语,因此要用关系副词when. 第二个空白处要填的关系词在从句中作动词spent的宾语,因此要用关系代词which或that来引导定语从句.
2）当主语为物时，不能用what
3）there be句型中，指人用who指物用that。
4）当主句中缺少主语或表语时，用the one。
5）当出现先行词+介词时，关系词只能用whom或which
6）当出现先行词+介词时，注意判断介词与从句谓语是否有关系，以确定为定语从句
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