OF后面为什么要加名词性物主代词?

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.

of在此是不译的，没有意思。所以of后面就要表示 谁谁的。

of在此是不译的，没有意思。所以of后面就要表示 谁谁的。
He is my father's friend. -- Make sense!
He is a friendHE IS A FRIEND OF MY FATHER'S, -- That means, my father has many friends, he is one of them. ...

of在此是不译的，没有意思。所以of后面就要表示 谁谁的。懂了吧