1. Nobody has cleaned the streets this week

-> The streets haven‘t been cleaned this week.

2. They will show the time machine to the public when they finish it.

-> The time machine will be shown to the public when it is finished.

3. the postman was bitten by our dog

-> Our dog bit the postman.

4. People are drinking more coffee than tea these days.

-> More coffee is being drunk than tea these days by people/

5. They think that I built an expensive hotel in the center of the city

-> An expensive hotel is thought to have built in the center of the city