IT'S A HABIT OF MINE!
In English, "I'm going to meet my friend tonight" is a rather sad remark.
"Why?" you ask, "surely you'll both have a good time!"
Yes, maybe we will. But it's sad because she's the only friend I've got!
If, on the other hand, the statement was
"I'm going to meet a friend of mine tonight."
then it's probably a happy occasion!
"Really? Which one?"
is perhaps the response. And a possible answer:
"Remember? The sexy blonde I met last week!"
To explain: "I'm going to meet my friend" means that I have only one friend.
Whereas "I'm going to meet a friend of mine" means I'm meeting one of my many friends.
"These are my friends" means they are the ONLY friends I have.
"These are friends of mine" means they are just some of my friends - I'm quite popular!
"That's my house" is usually correct!
I'd love to be able to say "Those are houses of mine!" meaning just some of my houses!
"Smoking is a nasty habit of hers."
It's especially sad here, because smoking is only one of her bad habits! But almost certainly the worst!
"Driving very fast is a hobby of his!" It's just one of his hobbies. I hope he survives to enjoy the others!
"Swimming is their pastime." (They exclude any other pastime)
"Swimming is a pastime of theirs." (But they have other pastimes, too)
"Painting pictures is a hobby of hers." (She has many hobbies)
"Painting pictures is her hobby." (She only has one hobby)
Ok - I'm off to my local now for a pint of ale! I've only got one local! Goodnight!