Dear Mary,
I would like to take this opportunity to express my heartfelt gratitude to you for your help when I was in difficulty. You have been very kind and helpful since we knew each other.
Last week, I caught a bad cold and had to stay at home for a week. When I was worrying about the lessons, you came to my home after school and helped me with every subject. With your help, I didn’t fall behind others.
Again, thanks so much for your enthusiastic help. Even though you are to about to go abroad for further education I know that I will always stay in touch with you. I wish you every success in the future and I hope we can exchange more viewpoints on study.
Please keep in touch, and drop in and visit us whenever you are in this part of the world.
Very sincerely,
Li Ming