都是连词.
and,so,but,or是并列连词,连接两个并列句,或并列的词,或结构.
and并且,和；so因此; but但是, or或者
I don't know the boy or the girl.
The boy and the girl are not my friends, but they want to help me, so I am very happy.
而because是个引导原因状语从句的从属连词.
He is happy because the girl wants to help him. 都是连词.
and,so,but,or是并列连词,连接两个并列句,或并列的词,或结构.
and并且,和；so因此; but但是, or或者
I don't know the boy or the girl.
The boy and the girl are not my friends, but they want to help me, so I am very happy.
而because是个引导原因状语从句的从属连词.
He is happy because the girl wants to help him.