如何辨别that和which在定语从句中是做主语还是谓语?我是初三的,现在学定语从句,不知道that和which在定语从

先行词在从句中的成分决定引导词在从句中的成分.
I love the girl.The girl is a football player.the girl就是先行词,在从句里做主语.变成定语从句时who 就是主语.I love the girl who is a football player.
I bought a book.The book was very interesting.The book是先行词,在从句中做主语.变成定语从句时which就是主语.I bought a book which was very interesting.
I bought a book .He wrote the book last year.the book是先行词,在从句中做宾语.变成定语从句时which就是宾语.I bought a book which he wrote last year.
that在定语从句里,可以用来替代who,whom,which.