ответ:

3. This is Mary's box

4. Susan's wheelchair is new

5. Correct.

6. Correct

7. Charles's dinner is delicious

8. Correct

9.correct

10. Martha is Andy's girlfriend

11. Correct

12. My sister's toaster is broken

13. correct

14. James's test was bad

15. The children's backpack are cute

16. This is my mother's birthday day

17. correct

18. Paul's bike is white

19. my brother's kite is yellow

20. correct