William: I am sorry to bother you so late but we need another parent to cover the ratio for our school trip.
David: I would love to go but I am having a meeting on that day that I really do not want to reschedule. 
William: My apologies for the last minute notice but I have just got a cancellation from another parent. I will have to cancel the whole trip.
David: I see. I will do my best and try to reschedule the meeting. 
William: Thank you so much. Please let me know as soon as possible. 
David: I will let to know as soon as I find out.
David will try to reschedule his meeting to go on his child's school trip, as another parent has withdrawn and the trip could be cancelled.