They are building a new ring-road round the city.
A new ring-road is being built round the city.
I didn't realise that somebody was recording our conversation.
I didn't realise our conversation was being recorded.
Somebody cleaned the room.
The room was cleaned.
They have postponed the meeting.
The meeting has been postponed.
When we got to the stadium, we learnt that they had cancelled the game.
When we got to the stadium, we learnt that the game had been cancelled.
A group of students are writing a song.
The song is being written by a group of students.
Somebody is using the computer at the moment.
The computer is being used at the moment.
They have built a new hospital near the airport.
A new hospital has been built near the airport.