Convert from active voice to passive voice and vice versa

I 1. They proved the case against him. 
2. They found the car later in the middle of Wales. 
3. Somebody had removed the numberplates. 
4. Somebody had seen him driving a mechanical digger. 
5. The police fined Mr and Mrs Dawn each 100 pounds.

II 1. What a dreadful noise! It sounds as if a pig is being killed by someone!
2. That old house will have to be pulled down.
3. The flight may have been cancelled. 
4. I always used to be woken up by by someone at 5.30 when I was in the army.
5. The post is delivered very early in the morning.