Whose cat is it? (grandpa)
This is grandpa's cat.
Whose book is it? (mum)
This is mum's book.
Whose bike is it?
This is uncle's bike.
Whose ball is it? (sister)
This is sisters's ball.
Whose flowers are these? (aunt)
These are aunt's flowers.
Whose cat is it? (dad)
This is dad's cat.
Whose book is it? (grandma)
This is grandma's book.