Dear Mrs. / Mr. XX,
　　I am just writing to say “thank you”.I used to be weak in English.You found my problem and helped me out.With your help I am now good at English.I still remember your smile on the day when I won first prize in the English speech competition.It was you who gave me the confidence.Thank you for teaching me things i need to learn, thank you for being there for me when i have any problems, thanks for your devotion and willingness to help me, thank you for the love you've shown to me. 　
　I am lucky to have a teacher like you. And no matter what kind of person I will become, you will always have your influence on me. You taught me how to study, how to live and evenhow to be a man. From you, I learned what kind of person I want to be and what I should get from life. This means everything to me.
　　My dear teacher, no matter what you will always have a special place in my heart and I will remember what I have learned from you and carry the knowledge through my life!
　　Best wishes!
　　Sincerely,
　　X X X