1. We've been working/We're working since 9 o'clock. 2. I've been cleaning/I'm cleaning my flat for the past two hours. 3. Look. Can you see Simon over there? He's been sitting/He's sitting in the corner. 4. "How long have you been/are you ill?" "Since yesterday." 5. Have you known Sarah/Do you know Sarah for very long? 6. I've been learning English/I'm learning English since last year. 7. They've lived/They live in London now. They've been/They're there for the last six months.