Answer:
4.2. That car belongs to my dad. It's his car.
4.3. These trainers belong to my sister. They're her trainers.
4.4. These bicycles belong to your family. They're your bicycles.
4.5. That house belongs to Tom and Mary. It's their house.
4.6. That digital camera belongs to me. It's my camera.
4.7. Those sunglasses belong to you. They're your sunglasses.
4.8. This guitar belongs to my brother and me. It's our guitar.
4.9. The watch belongs to Jeff. It's his watch.
4.10. The notebooks belong to you and Mark. They're your notebooks.
5.
A: That is your pen!
B: Yes, and this is my pencil.
C: Here is his eraser too!
B: Look, my eraser!
A: I have our books right here.