I am truly sorry that ______（道歉的原因）. The reason is that ______（介绍原因）.
Once again, I am sorry for any inconvenience caused.
Hope you can accept my apologies and understand my situation.
1. I am writing this letter to express my regret… 我写这封信是想表达我的遗憾......
2. I am writing to apologize for… 我写信是为......道歉
3. I would like to give you my apology for… 我想为......向你道歉。
4. I am very sorry to say that…我很抱歉......
5. I must apologize about (not) doing sth…对于做了/没做......，我必须道歉。
6. Please accept my sincere apology for…请接受我对于......的真诚道歉。
7. I am writing to say sorry for…我写信是想对......说抱歉。
8. I am terribly sorry, but…我很抱歉，但是......
1. Once again, I am sorry for any inconvenience caused. 我对于所造成的任何不便再次道歉。
2. Please allow me to say sorry again. 请允许我再一次说抱歉。
3. Hope you can accept my apologies and understand my situation. 希望你们能够接受我的道歉，理解我的处境。
4. I sincerely hope that you will be able to think in my position and accept my apologies. 我真诚的希望你能够站在我的处境想一想，并且接受我的道歉。
5. I want to let you know how regretful I am feeling now. 我想让你知道我现在感觉多么的遗憾。
6. I am sorry that I can’t… but trust that you will be able to understand. 很抱歉我不能......，但我相信，你会理解的。
I'm terribly sorry to tell you we'll not be able to watch the Beijing Opera performance as planned. Words fail me to convey my deep regret.
Although I have been expecting to watch the performance with you, the fact is that most outdoor activities are forbidden due to COVID-19. That is why the performance has been canceled.
Luckily, there are many videos of Beijing Opera performances on the Internet available for free. It is a great chance to experience Chinese traditional culture and entertain ourselves. I'm sure a video will be a feast for eyes. In addition, there are scheduled performances next month for us to choose from.
I would appreciate it if you could give me an early reply.