Поставить следующие предложения в пассивный залог: 1. people send their complaints to the head office. 2. we are preparing your order for shipping. 3. the students will study new life forms. 4. john has repaired the bike.

1Their complaints are sent to the head office.
2 Your order for shipping is being prepared by us.
3 New life forms will be studied by the students.
4 The bike has been repaired by John.