Possessives with of

We cannot put a possessive between a noun and a determiner. We can say my friend, his friend, John's friend, a friend or that friend. But we can't say a my friend or that John's friend. Instead we use a structure with of + possessive.

Structure: determiner + noun + of + possessive

• He is a friend of mine.
• How is that brother of yours?
• He is a friend of my father's.
• He is a cousin of John's.
• Have you heard this new idea of the boss's?

Note that sometimes we use a noun without the possessive 's after of.

• He is a friend of my father.
• He is a cousin of John.