Преобразуйте действительную конструкцию в страдательную форму.
1. The teacher explains new material every day.
2. The teacher is explaining new material now.
3. The teacher has explained new material.
4. The teacher has been explaining new material for 15 minutes.
5. The teacher will explain new material tomorrow.
6. My friend keeps two dogs.
7. The veterinarian examines the horse.
8. The scientist proved cell division in this disease.