一、定语从句中的基本概念。
1)定语从句：修饰名词或代词的从句叫定语从句。
2)先行词：位置在定语从句前，被定语从句修饰或限制的对象叫先行词。现在我们来全面理解先行词：
① 先行词可以不只是一个词。尽管我们他这个对象称为先行词，但它不一定就是一个词，它可以是：
A.一个词
The woman who lives next door is a famous singer.
He who hesitates is lost.
B.短语
He likes climbing mountains, which is a good exercise.
C.一个分句
He said that he had no time, which is not true.
D.一个完整句子
He arrived an hour later, which annoyed his girlfriend very much.
My girlfriend likes chatting online with other guys, which really drives me crazy.