初中英语定语从句：在复合句中修饰名词、代词的从句叫定语从句。其先行词有指人 who /that；指物 which/ that。定语从句一般紧跟被修饰的名词或代词(即先行词)后。
一、定义
在复合句中修饰名词、代词的从句叫定语从句。
二、先行词
先行词指人 who /that
先行词指物 which/ that
定语从句一般紧跟被修饰的名词或代词(即先行词)后
三、关系代词
关系代词代替先行词在句子中担当成分，所以从句中不可再出现其他代替先行词的代词
四、翻译方法 “…. 的”
Whom: 先行词指人，则代替先行词在定语从句中充当宾语(包括介词的宾语), 与who的区别是如果前面带介词则必须用whom
1. This is the teacher whomwho we like best.
2. I don’t like the boy to whom you are talking.
Whose : 指人或物，作定语，表示 “…的”
eg: Harry is the boy whose mother is our math teacher.
关系代词只能 that 的特殊情况：
1.先行词前有序数词修饰时：
This is the first gift that my parents bought me.
2.先行词前有形容词最高级修饰时：
This is the most exciting film that I have ever seen.
3. 先行词是不定代词something, anything等时.
e.g. Is there anything that you want in this shop
4. 先行词是人和物时, 用that.
e.g. He talked about some writers and books that were unknown to us all.
5. 先行词被all , little , the only , the very(就是，正是), the last 等词修饰时,只能用that
e.g. This is the last place that I want to visit.
6. 特殊疑问句以who 或which 开头，只能用that引导.
Who is the girl that is making a speech on the platform?
当关系代词前使用介词时：
物+介词+which ; 人+ 介词 + whom
当关系代词前使用介词时：
e.g. 1. This is the train by which we went to Beijing.
2. This is the teacher to whom my mother is talking.