高三数学网上补习机构

　　●锦囊妙计

　　②非限定性定语从句是对主句先行词的补充说明，没有这种从句不影响主句意思的完整，一般用逗号把主句和从句分开。关系代词用which，不用that;指人时可用who，例如：

　　I have two sisters, who are both students.

　　Crusoe’s dog, which was now very old, became ill and died.

　　6.as引导的定语从句：

　　①as用作关系代词和关系副词引导限定性定语从句，并在从句中作主语、表语或状语，构成the same…as, such…as等结构。例如：

　　I like the same book as you do.(as作宾语)