Make the following sentences passive.

1. Jilles de Dion built the first mechanically propelled vehicle.

2. They have already sent the letters.

3. They were asking him questions for 2 hours.

4. The factory workers will appreciate improved conditions of work.

5. The mechanic is repairing Bill's car?

6. An architect didn't design this house.

1) the first mechanically propelled vehicle was built by Gilles de Dion.

2) the letters have been already sent by them.

3) He was being asked questions for 2 hours by them.

4) Improved conditions of work will be appreciated by the factory workers.

5) Bill's car is being repaired by the mechanic

6) This house was't designed by an architect.