Can I use your CD player?
Yes, you can.
What's the answer?
Our / Their
Is this your book? Yes, it's.... book.
Yes, it's our book.
Can I use your MP3 player?
No, you can't.
Is this your ice-cream? No, it's .... ice-cream.
No, it's their ice-cream.
Can I use your camera?
No,you can't.
Can I use your TV?
Yes, you can.
What's the answer?
my / her (or your)