额.....给你提供几个句子吧。
My dear teacher,in this special day， I thank you so much for your hard work （亲爱的老师，在这个特殊的节日我感谢你如此辛勤的耕耘！）
Wish you happiness and health forever！（愿您永远幸福安康。）
I would like to thank you for all the help you gave me during this past semester. （非常感谢您这学期对我的所有帮助）You were alway so patient when I asked you questions.（您总是如此耐心地回答我的问题） You listened to ours carefully and explained everything so thoroughly.（您仔细的听诉我们的疑难，彻底的为我们解释所有） You showed me different ways to practice and remember new words and usage. （您向我展示了不同的练习、记忆新单词的方法）I felt so encouraged and became more comfortable in speaking English. （我感觉到了您的鼓励，变得越来越倾心于说英语）You made the excercise so interesting that I was always very eager to participate and practice.（您将练习变得如此有趣以至于我渴望参与与锻炼） My English has improved so much.（我的英语提高了很多） How could I thank you enough?! （我怎样才能谢谢您？）
Sincerely yours（您真挚的* *）
额.....复制来的，删了一点，增了一点，帮你翻译好了，但有的只是意翻译，希望能帮到你。
参考资料：百度 自身