感谢信是就某事向收信人表示感谢的信件，分为三个部分：
1. 指出对方帮助自己的事情，表示感谢；
2. 展开叙述这件事；
3. 再次感谢，并可表示希望回报对方。
Suppose you were taken good care of by Doctor Liu when you were in hospital. Write a letter in about 100 words to him to show your gratitude. Do not sign your own name at the end of your letter， using Li Ming instead.
Sample：
Dear Doctor Liu，
It is a great pleasure to extend my sincere thanks to you for your careful treatment and attendance when I was in hospital this March.
On that night， I got acute appendicitis and was sent to your hospital by my roommates. Yet I was very lucky to have you， an experienced and skillful doctor， on duty. You immediately diagnosed my disease， hospitalized me and arranged a timely operation for me. In the following days you took good care of me and talked to me from time to time to release my pain.
It was all because of your attendance and perfect professional skills that I could recover so soon. Therefore， thank you again and I wish I would have the chance to pay you back for all your kindness.
Yours faithfully，
