dear______：
i am writing to extend my sincere gratitude for _________ (感谢的原因).
if it had not been for yourassistance in ___________ (对方给你的具体帮助), i fear that i would havebeen_________(没有对方帮助时的后果).
every one agreesthat it was you who______________(给出细节).again, i would like to express my warmthanks to you!
please accept my gratitude.
yours sincerely