Ответ:

  1. Whose computer is this? — It’s Tina’s. It’s her computer. It’s hers.

  2. Whose camera is this? — It’s Bob’s. It’s his camera. It’s his.

  3. Whose watch is this? — It’s Tony’s. It’s his watch. It’s his.

  4. Whose skateboard is this? — It’s Bill’s. It’s his skateboard. It’s his.

  5. Whose ball is this? — It’s Paul and Ann’s. It’s their ball. It’s theirs.

  6. Whose suitcase is this? — It’s Pat’s. It’s his/her suitcase. It’s his/hers.