Form general or special questions with the question word given. 1) we have been friends since childhood. (since when) 2) the rain hasn't stopped yet. (general) 3) the film has been on for a week (for how long) 4) he had recovered by the time i returned from my leave. (general) 5) he will have worked as a teacher for 20 years by next semptember. (for how long) 6) the students will have started the discussion by the time you come. (who)