Помогите PLEASE! Передайте следующие предложения в Passive Voice.

хотя бы перевернула бы. .
you must be done

1 Three of these exercises have to be done by tomorrow.
2 This book can be found in any library.
3 These letters must be sent at once
4 This box must be taken to the station.
5 The river can be crossed on a raft.