干脆给你重写一篇得了
用的是稍正式的语体
Dear Guy,
Thank you very much for your hospitality during my stay in the United States, and I am grateful that you were so kind as to help me to get myself familiarized with American culture within so short a time. With your help, not only did I acquire a lot about American values as well as customs and thus got over the culture shock, but also I achieved the exchange program objectives as scheduled.
I was deeply impressed by the sense of responsibility and commitment shown by my American partners during the program. Honestly, I had never experienced so much before about the diversity, dynamism, and independence of the American culture. Now, I really treasure all the memories you brought to me. All in all, it was truly a rewarding trip.
With all those happy days, I feel it is necessary for us to strengthen our friendships and in order to further the exchanges and enjoy more benefits, I sincerely invite you to pay a visit to China. I am sure you will be fascinated by a same great but different oriental culture here --- the Chinese culture.
I am looking forward to your China trip.
Yours sincerely,
Zhang Wei
(注,如果对方的名字不是Guy, 那就得注意换个名字)