Dear Mr Li,
I'm very excited to write to express my thanks to you. I am now a freshman of Wuhan University, which I have been dreaming about. Mr Li, I still remember the days when you taught me English. My English has been improved greatly because of your creative work. However, at one time, the pressure of examinations, too much homework and the high expectations made me depressed. I was tired of the warning that if I didn't do my best, I wouldn't have the chance to go to college. Thanks for your encouragement; if not, I wouldn't have realized my dream. And now I really understand you. I wish more and more of your students could go to their ideal colleges. Are you still so busy? How I miss you!
Hoping to hear from you soon.