1) Someone was repairing their bikes.

Their bikes were being repaired.

2) Who is checking the passports?

Who are the passports being checked by?

3) We were fixing the satellite dish at 7p.m. yesterday.

The satellite dish was being fixed at 7p.m. yesterday.

4) One of the cable TV channels is presenting a new quiz show.

A new quiz show is being presented by one of the cable TV channels.

5) Newton discovered the law of gravity.

The law of gravity was discovered by Newton.

6) A building team was building the house when we returned to the town.

The house was being built by a building team when we returned to the town.          

7) Cole Porter composed some nice musicals.

Some nice musicals were composed by Cole Porter.

8) Someone was turning off TV while I came in the room.

TV was being turned off while I came in the room.

9) Students handed out fliers last week.

Fliers were handed out by students last week.

10) At this very moment we are watching the soap opera on TV.

At this very moment the soap opera is being watched on TV.

11) Journalists usually interview a variety of people.

A variety of people are usually interviewed by journalists.