定语从句跟在名词或代词后,作定语
如:This is the girl whose mother is a teacher.
He likes everything that his mother buys for him.
宾语从句跟在动词、介词、形容词、动词短语、双宾语后,作宾语
如:I don't know waht he is good at .
He is interested in whether he has passed the examination.
I am sure that you will succeed.
Please find out who has broken the window.
Will you tell him how he can get to the railway station?