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.