( И ОБЪЯСНИТЕ , КАКОЕ ЭТО ВРЕМЯ И ПОЧЕМУ. ) Например: (1 somebody has cleaned the room. The room has been cleaned)
2 they have postponed the meeting. the
3 somebody is using the computer at the moment. the computer
4 i didn't realise that somebody was recording our conversation. i didn't realise that
5 when we got to the stadium, we found that they had cancelled the game. when we got to the stadium, we found that
6 they are building a new ring road round the city,
7 they have built a new hospital near the airport.