1. The ball is being thrown by Jessica.

2. The job offer was accepted by her.

3. A kite is being flown by that child in the park.

4. The painting will be sold by Barbara in the future.

5. (can't be turned to passive voice because it doesn't have any object).

6. Steve's project was forgotten by him at home.

7. An art fair is being organized by my teacher.

8. (can't be turned to passive voice).

9. The new lady shop was designed by Paul.

10. The sculptures were finished by George two days ago.

11. Dinner has been eaten by us.

12. The robber is no where to be found by the police last night.

13. Her friend has waited for her at the mall.

14. A French film was downloaded by me yesterday.

15. A cheery song is sung by the bird every morning.

16. The politician was asked by the journalist some difficult questions.

17. The actors had been chosen by them.

18. My teeth were checked by the dentist.

19. An apartment was bought by my aunt.

Hope this helps!