Dear Teacher X, thank you for teaching us mathematics for many years. With your attitude of setting an example by yourself, you set a life example of being strict with yourself. With your example and serious spirit, we not only learned mathematics knowledge, but also understood our responsibilities as successors of this country. At this parting moment, let's express our sincere feelings, study hard and don't let the teacher down. Let's say it again from the bottom of our hearts: thank you for your teaching and patient help!