一、定语从句的概述
    
        
            | 定义 | 在主从复合句中, 对某一名词或代词起修饰限制作用的从句 | 
        
            | 先行词 | 被修饰的名词或代词叫先行词 | 
        
            | 关系词 | 关系代词 who;   whom; whose; which; that;  as 关系副词 when;   where; why | 
        
            | 分类 | 可分为限制性定语从句和非限制性定语从句 | 
    
 
*The meeting that you have missed yesterday was very  
  (先行词) (限制性定语从句,  that为关系代词)
important. 你昨天错过的会议非常重要。
*Beijing,  which is the capital city of China,  is a very  
(先行词) (非限制性定语从句,  which为关系代词)
beautiful city. 
北京是一座非常美丽的城市, 它是中国的首都。