Dear______，
I am writing to express my heartfelt gratitude to you for ______.
If it had not been for your assistance in giving me aid and ______, I fear that ______. /Without your help, I would not have done______ .During the ______, you have given me generous help and continuous guidance by______ .Thus, I really appreciate______ , and I hope that I may repay your kindness by ______.
Finally, I feel most obliged to thank you once more.
Yours sincerely,
Li Ming