Найти ошибку в предложениях и исправить на правильный вариант.
1) I am sorry I haven't written to you since by then as I have been working abroad,
2) Just a quick note to explain what we have been done so far this month.
3) As the weather has been bad we had been working inside most of the time.
4) Warning of storms ahead, the climbers reluctantly returned to the camp.
1 by убрать.2.done на doing поменять,3.has been на was, had been на were, 4 warning на warned.