语法专题一 定语从句
定语从句在句中作定语，修饰名词或代词。被修饰的名词或者代词被称为先行词，定语从句一般放在先行词的后面。引导定语从句的词被称为关系词，关系词有关系代词和关系副词，它们在先行词和定语从句之间起引导作用，在意义上代替先行词，在定语从句中充当一个成分。其基本解题方法是：第一，找出先行词；第二，看先行词在定语从句中充当的成分，作主语、宾语、表语或定语时要用关系代词，如果作状语，则要选用关系副词；第三，看先行词是否为特殊词，然后根据需要选用合适的关系词。
考点一 关系代词与关系副词的区别
关系代词有who，whom，which，that和whose，另外，as也可充当关系代词。关系代词在定语从句中充当主语、宾语、表语和定语。关系副词有when，where和why，在定语从句中充当状语。
1．who指人，在定语从句中作主语或宾语。
The boys who are playing football are from Class One.
2．whom指人，在定语从句中作宾语，常可省略。
Mr Liu is the person (whom) you talked about just now.
3．which 指物，在定语从句中作主语或宾语，作宾语时常可省略。
The book which he gave me is very interesting.
4．that 指人时，相当于who 或whom；指物时，相当于which。在定语从句中作主语或宾语，作宾语时常可省略。
She is the pop star (that) I want to see very much.
5．whose可指人或物，修饰名词或代词，在定语从句中充当定语。“whose＋名词”可改为“the＋名词＋of which/whom”或“of which/whom the＋名词”。
The house whose windows are very large is my uncle's.＝The house of which the windows are very large is my uncle's.
