✔ 最佳答案
Dear Sir,
Thank you very much for the invitation to your Dinner Party / Annual Dinner / Celebration Party (自選其一) on the XXth October 2008 at the ZZZ Hotel / YYY Restaurant.
With much regret I am otherwise engaged and therefore am unable to attend your function.
Please accept my apologies and my best wishes for a wonderful event / delightful party / beautiful evening (自選其一) .
Yours truly,
Mr. Lau
(pp. Your Name)
藍色字嘅請根據你的資料自已填番
2008-10-07 15:26:29 補充:
(pp. Mary Chan) = Mary Chan 代行 / 代筆