Форма общие или задать вопрос : 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 September, (for how long) 6. The students will have started the discussion by the time you come, (who)