my,mine,our,ours

1. I bought a cake. It is my cake. The cake is mine.
2. We have a dog. It is our dog. The dog is ours.
3. You have a chocolate.That is your chocolate.
4. That chocolate is  yours.
5. He has a sister. This is his sister. That sister is his.
6. She has a purse.This is her purse.The purse is hers.
7. The cow has a tail. It is its tail.The tail is its.
8. They have a house.This is their house.That house is theirs.
9. You all have lessons.Those are your lessons.
10. Those lessons are yours.
11.