Present perfect continuous (I have been doing)

You meet Paul as he is leaving the swimming pool.
You ask: (you / swim?)

You have just arrived to meet a friend who is waiting for you.
You ask: (you / wait / long?)

You meet a friend in the street. His face and hands are very dirty.
You ask: (what / you / do?)

A friend of yours is now working in a shop. You want to know how long.
You ask: (how long / you / work / there?)

A friend tells you about his job - he sells computers. You want to know how long.
You ask: (how long / you / sell / computers?)