道歉信(apologies)
march 14, 2001
dear mr. li:
    i am sorry that i must apologize for not being able to help you when you asked me to give you a letter of introduction to the director of the national institute of oncology of my country. 
    unfortunately i didnt see director tom carter of the national institute of oncology those days and i had no chance of mentioning your name to him. because he was in a hospital.
i will certainly mention you if i happen to run into him. i hope you will do well in your research work.
yours sincerely,
e.s.jones(signed)