1. How long have you been a police officer? Since
2. How long has your mum worked in the factory? She's worked there for eleven months.
3. How long has your grandpa lived in that house? He's lived in it since she was 30.
4. How long have your friends been in the canteen? For a long time!
5. How long have you been I've been here for two hours!
6. How long have they studied at the university? Since last year. English? Since 2009.