Whose car is this?
It's the boy's car. It's his car.
Whose plane is this?
It's the boy's plane. It's his plane.
Whose tablet is this?
It's the boy's tablet. It's his tablet.
Whose ball is this?
It's the boys' ball. It's their ball.
Whose doll is this?
It's the girl's doll. It's her doll.
Whose house is this?
It's the boy and girl's house. It's their house.
Whose kite is this?
It's the boy's kite. It's his kite.
Whose bike is this?
It's the girl's bike. It's her bike.
Whose blocks are these?
They're the girl's blocks. They're her blocks.