1. It's her handbag. It's hers
2. It's my T-shirt. It's mine.
3. They're his trainers. they are his.
4. It's his
5. It's theirs.
6. They're ours.
7. They're your books.
8. It's hers.
Если ты сам это задание писал, то знай, что неодуш предметы не they, а these. Но если тебе так сказали, то ничего не меняй