Напиши полную форму например-it's-it is they're-they are what this? it's daddy's that's my doll. they're mum's. what's wrong? they're pencil cases. it's a tea set.

What is thius?
It is Daddy's.
That is my doll.
They are mum's.
What is wrong?
They are pencil-cases.
It is a tea set.