做错了事就要主动承认错误，说不出口就写个道歉信吧。
Dear David:
I am afraid that you will think me unpardonably negligent in not having answered your letter dated 7, December sooner, but when I have told you the reason, I trust you will be convinced that the neglect was excusable. When your letter arrived, I was just in Hong Kong. As my family could not forward it to me during my absence, it has been, therefore, lying on my desk until the moment when I took it up. Now the first thing I have to hasten to do is to write to you these few lines to express my deep regret.
I enjoyed many pleasant sights during my trip. I shall be pleased to give you an account to of them when I see you next.
Sincerely yours,