In the lost and found case:

In the lost and found case:
A:Can I help you?
B:I can't find my ( )
A:Is it on the desk?
B:No,( )isn't.
A:Is ( ) your backpack?
B:No,it ( ).My backpack is( ).That one is small.
A;What about this one Is it (
B:No ,( )is blue.This one is green.
A:How about that one over there?
B:Yes,( )is my backpack.look,it has my name ( )it.Thank you
very much.
A:You're ( ).