How long have you been in London ?
I have been there for 5 days .
How long have you been in school ?
I have been there for 7 hours.
How long have you been dancing ?
I have been dancing since I was 5 .
How lon have you been writing this letter ?
I have been writing this letter for 10 minutes.
How long have you been at your mother ?
I have been am my mother since my father goes working .