1、of which相当于定语whose，后加名词，相当于是一个形容词。
eg：There are many books in the shelf, of which/whose covers are old.
书架上有许多封面陈旧的书。
2、in which相当于疑问词where，是对地点名词的修饰。
eg：The book （in which/where there are many stories） in his.
这本有许多故事的书是他的。
3、on which相当于特殊疑问词when，是对时间的修饰。
eg：I will never forget the best time when/on which we enjoyed ourselves.
4、for which相当于疑问词why，是对原因的修饰。
eg：I don't the reason why/for which he was late.
我不知道他迟到的原因。
5、at which相当于疑问词how，是对方式名词的修饰。
