一封道歉信　　dear prof.
wang, 　　i m writing to ask you to excuse me for not being able to keep our appointment.
i do know that this is very impolite and must have caused you much trouble.
　　i do reckon that at present any explanation is pale and futile.
however i do not want you to misunderstand me.
on my way to your office, an old lady suddenly fainted due to heart attack on the bus.
i stopped a taxi and sent her into a nearby hospital.
i stayed there until her son came, which spoiled our appointment.
　　i am aware that our appointment is of importance.
i do hope that you would be kind enough to spare your valuable to meet me.
　　i am looking forward to hearing from you.
　　sincerely yours