①表达歉意

►I sincerely apologize to you for…

►I am indeed very sorry for …, but believe I had no intention to…

► I am writing this letter to apologize to you for my failing to…

② 解释苦衷

► …due to my toothache/traffic accident/traffic jam国防生考研

►… as the things is quite beyond my power to do

► …because I have to deal with the urgent business assigned by my boss

③ 提出补偿建议+再次道歉

►I want to know if we could…

►I wonder whether it is possible that I make up the loss by…

►Please forgive me for/accept my deepest apology for …

►I do hope that you can understand my situation and accept my apology.