Whose cat is this?
It's Mark's cat.
Whose crayons are these?
They're Mark's crayons.
Whose apple is this?
It's Susan's apple.
Whose dog is this?
It's Susan's dog.
Whose rulers are these?
They're Susan's rulers.
Whose doll is this?
It's Susan's doll.
Whose books are these?
They're Mark's books.
Whose dress is this?
It's Susan's dress.
Whose glasses are these?
They're Mark's glasses.
Whose cap is this?
It's Mark's cap.
Whose ball is this?
It's Mark's ball.