定语从句：人 物
1.主语 who/that which/that
2.宾语 who/whom/that/省略 which/that/省略
3.定语 whose the n.of which/whose
4.表语 that that
5.状语
不能用which只能用that：
1.先行词本身是不定代词all/everything/anything/nothing/much/few/little/none/the one
2.先行词被一些词修饰（序数词,最高级）only/few/any/little/no/all/every/very
3.先行词中既有物又有人
4.who/which/that开头
只能用which不能用that
1.在非限定从句,先行词是物
2.先行词本身是that
3.当关系词前面有介词
只能用who不能用that
1.先行词是one/ones/anyone/those/I/you/he/they
2.先行词是人,后面有较长的修饰词
3.there be开头
4.在非限定从句,先行词是人
5.在介词前置时只能用whom
one of n.（复数）+定语从句 定语从句中谓语用复数
the only one of n.（复数）+定语从句 定语从句中谓语用第三人称单数
区分定语从句和强调句：把it is…that去掉,若句子完整是强调句
eg：it is the Suez Canal that separates Asia from Africa.
It is/was +被强调部分+that+句子剩余部分
若先行词是situation之类的抽象名词,用in which/where
先行词是the way 做方式状语,用 in which/that/省略
the same …as 表示同一类事物
the same …that 表示同一件物品
eg：this is the same bike as I lost.
This is the same bike that I lost,so I take it home.
He has four daughters,none of whom is a pianist as he is.
He has four daughters.None of them is a pianist as he is.
He has four daughters,and none of them is a pianist as he is.