结构要点：
致歉信是向收信人表示歉意的信件，包括三个部分：
1. 说明为何事而致歉;
2. 解释造成过失或不能履约的原因;
3. 再次致歉或提出解决方案。
Directions 9
Suppose you cannot attend your sisters graduation ceremony as expected for some reason. Write a letter in about 100 words to make an apology to her. Do not sign your own name at the end of your letter， using Li Ming instead.
Sample：
Dear Linda，
Kindly excuse me for my not being able to attend your graduation ceremony next Wednesday as I have promised.
You know， there will be a meeting of great importance to my company next week in Nanjing. But the person who was originally appointed to it is now seriously ill in hospital. And I have been asked to take his place to attend the meeting and make a speech on behalf of my company. On the one hand， it is a task assigned by my boss out of his trust in me. On the other hand， I do regard it as an opportunity to both display and enhance my abilities. So I am afraid I cannot be present at your graduation ceremony.
Though I have decided to send you a gift to celebrate your graduation， I really regret that I cannot give you my sincere congratulations on the spot， for I know any gift can never parallel a warm word spoken personally by a family member. I do feel terribly sorry. Please forgive me.
Cordially，
Li Ming
