How to express your disappointment to the teacher?

If you change teachers halfway and don't give up, there is the following sentence:

1, teacher, you are the most unforgettable person in my life. Because of you, my life has become interesting and my life has changed because of you. Thank you.

2. After a busy year, dear teacher, your New Year is here again. Thank you for your help and concern, and everything you have done for us. No matter when and where, you will always be my good teacher!

3. In the future, whether I am a tall and straight tree or a low shrub, teacher, I will pay tribute to you with the green of life!

4. Hello, teacher. A thousand words can't express my gratitude. I only say one thing from my heart: Happy New Year's Day, teacher. I wish you a better tomorrow.

5. You have propped up my ideal sail; You lit the fire of my knowledge. You are the person I respect all my life!