To emphasize the action rather than the actor
1.After long debate, the proposal was endorsed by the long-range planning committee.
To keep the subject and focus consistent throughout a passage
2.The data processing department recently presented what proved to be a controversial proposal to expand its staff. After long debate, the proposal was endorsed by . . . .
To be tactful by not naming the actor
3.The procedures were somehow misinterpreted.
To describe a condition in which the actor is unknown or unimportant
4.Every year, thousands of people are diagnosed as having cancer.
To create an authoritative tone
5.Visitors are not allowed after 9:00 p.m.