Pronouns

Subject	Object	Possessive adjective	Possessive pronoun
I I write letters	Me Who writes letters? Me	My These are my letters	Mine These letters are mine
You You write letters	You Who writes letters? You	Your These are your letters	Yours These letters are yours
He He writes letters	Him Who writes letters? Him	His These are his letters	His These letters are his
She She writes letters	Her Who writes letters? Her	Her These are her letters	Hers These letters are hers
It It writes letters	It Who writes letters? It	Its These are its letters	–
We We write letters	Us Who writes letters? Us	Our These are our letters	Ours These letters are ours
They They write letters	Them Who writes letters? Them	Their These are their letters	Theirs These letters are theirs

We can use possessive pronouns and nouns after OF. For example:

Sam is one of my friends = Sam is a friend of mine (possessive pronoun)

I am one of Sam’s friends = I am a friend of Sam’s (noun)