OF后面为什么要加名词性物主代词?例如HEISAFRIENDOFMYFATHER'S.为什么是MYFATHER'S,而不是MYFATHER?越详细越好,

Question

OF后面为什么要加名词性物主代词?
例如HE IS A FRIEND OF MY FATHER'S.为什么是MY FATHER'S,而不是MY FATHER?越详细越好,

Answer 1

He is my father's friend.-- Make sense!
He is a friend of my father -- Dose not make sense!
HE IS A FRIEND OF MY FATHER'S,-- That means,my father has many friends,he is one of them.
Try to think it in a natural way,instead of grammar analysis.More reading and writing will be helpful.