Dear sir :
I am very glad that you are my teacher,You are one of the best teachers who I know .there are many good points what we should learn from you,such as kindness,patience,humor and so on.please forgive me that I had made so many mistakes which make you always angry.I really want to be a good student.Thanks for you teaching ,I have learn so many interesting things ,so many words,so many sentencesform you,Ican feel that it is not only a progress of learning,but also a convarcation of feeling . You are my teacher and good friend, We are the lucky dogs that we have such teacher as you.finally,I hope you happy everyday!
best wishes
your student
人称替换一下就行