Поставьте следующие предложения во множе¬ственное число.
1. This cup is dirty. 2. That biscuit was tasty. 3. This hotel is very expensive but it's very nice. 4. There is a children's playground in the park. 5. That was a new supermarket in our town. 6. It's a delicious lemon pie for dessert. 7. It's a nice cot¬ton dress for my niece. 8. This man was an engineer. 9. That woman is my sister. 10. This child is my son. 11. That goose is big. 12. This mouse is white. 13. This man is a doctor.