书面表达。     假设你是李华，曾在美国学习半年，现已回国。你想联系你的美国老

One possible version:
Dear Tom,
      I am now back China and sound. In this letter I would like to convey my heartfelt appreciation to you for
your kind assistance in my English learning when I was in New York. Additionally, your generous help and
tender care made me feel warmly welcomed and transformed my first American trip into a unforgettable
memory.
     I have been missing our English professor, Mr. Smith whose unusual cast of mind, wide and varied
knowledge, together with a singular personal charm, combined to exert a strong influence on me. What about
him recently? I desire to contact him for some suggestions on improving my listening ability. However, his
email address is not available. So would you mind delivering it to me via the online mailbox?
      I am more than delighted to invite you to join us to celebrate the Spring Festival -Chinese Lunar New Year
so that I can repay your friendship. You can partner with me to have a try in lion dances ,which is extremely
exciting. And the grand lantern festival parade will be bound to impress you. I assure you that you would enjoy
visiting here as I did at you home.
     With my best regards!                          
                                                                                                                        Yours cordially,
                                                                                                                               Li Hua