Take the following example;
Dear teacher, thank you for your concern, your help and everything you have done for us. Please accept our best wishes.
Some people say that the teacher's kindness is like a mountain, and the mountain stops. As the saying goes, "new bamboo is taller than old bamboo branches, and it is all supported by old cadres." A little progress and some achievements of the whole class are all condensed with your efforts. Therefore, no matter when and where, no matter the ends of the earth, you are our teacher and we are all your students.
It is your eyes that guide us and your words that comfort us. Whether you are frustrated or happy, your inner light will always accompany us. You sow with words, cultivate with chalk, water with sweat, and moisten with hard work. Every silver thread of yours has witnessed our growth process, and every wrinkle of yours is deeply engraved in our hearts.
Dear teacher, please rest assured that our students will remember your earnest teachings and live up to your earnest hopes. In a beautiful and tree-lined school, they will, like those old and new alumni who have made great achievements, have greater ambitions, hold higher ideals, study hard, strive to become the pillars of the country, and repay the high hopes and training of the school with fruitful results and brilliant achievements.
To my dear teacher.