1. The police are holding him for further questioning.
=> He is being hold by the poilive for further questioning.
2. Somebody has locked the box and I can't open it.
=> The box has been locked and I can't open it.
3. He shouldn't do that silly thing.
=> silly thing shoudn't be done
4. My sister gave me a new jean on my birthday.
=> a new jean was given to me by my sister on my birthday.
5. The workers are building a hotel on this street.
=> a hotel is being built by the workers on this street.
6. The zoo keepers feed the animal twice a day.
=> the animal is feeded by The zoo keepers twice a day.
7. They have sold their car to pay the debt.
=> Their car has been solden to pay the debt.