Dear Mr. Smith,
I am indeed very sorry that I missed the examination on International Business English Writing you gave last Friday. I feel awful about it and want you to know what happened that day.
I suddenly fell sick early that morning and my parents had to send me to the hospital. Please find enclosed a copy of the medical bill.
I sincerely hope you can understand my situation and accept my apology. I would appreciate your allowing me to take a make-up examination. I will come to your office during your office hour on Monday to discuss this possibility with you. Once again, I apologize for any inconvenience caused.
I am writing to express my apology to you for my failing to return your music CD before I came back.
Several days ago, I borrowed it when I lived in your house. Unfortunately, just now I found it in my luggage. I was in such a hurry that I forgot to return it to you. I will send it to you by post or express as soon as possible. If necessary, I will compensate for any troubles it may cause.
Once again, I feel so sorry for any inconvenience caused. Please accept my apologies.
第一段首先亮出写作目的并简单阐述该物品的状态：I am writing to make an apology to you for+句子(表明事件因由)。
第二段列出出错的原因及具体补救办法：To make up my fault, ......\ I will......as a token of my apology\ I sincerely apologize for my careless mistake as well as for any inconvenience thus caused to you.
第三段再一次表达歉意：Once again, I am sorry for my carelessness. Looking forward to your reply.