关系副词的相关知识点（三）

2）where表地点，只能跟在表示地点的名词后，它在定语从句中作地点状语。
        例如：This is the second school where I used to teach. 
        注意：
        ①引导词where可用that替换，并经常可以省略。
        例如：That's the place(where/that) we went before. 
        ②当表示地点的先行词在句中作主语或宾语时，不用where，用关系代词that或which。
        例如：The factory that/which we visited yesterday was built last year. 
        ③where可与from连用。
        例如：His head soon appeared out of the second story windows, from where he could see nothing but rees. 
        3）why表原因，引导的从句修饰名词reason。Why可用that或for which替换或省略。
        例如：I don't know the reason(why/for which/that) he left here.