①I am truly sorry that ______(道歉的原因).
②The reason is that ______(介绍原因).
③Once again, I am sorry for any inconvenience caused. ④Hope you can accept my appologies and understand my situation.
I am writing this letter to apologize to you for my failing to .
The reason is that ______ . I am sorry that I cannot finish in time, but is it possible that I make up the loss by ? If so, I will put everything else aside to .
I do hope that you can understand my situation and accept my apology.
Much to my regret / I am terribly sorry that I am unable to ______ . It is mainly because at that time I will be full occupied by which is quite out of my expectation, and that conflicts with your . Therefore I am forced to adjust my schedule and cannot make my presence on your . I sincerely hope that you will enjoy a good time. By the way, can we have dinner together some time next week? I hope to see you soon. I am really sorry again and I trust that you will understand.