Dear Mr Lee,
I was very glad to get your letter. Thank you for your invitation. I'd like to go to your beautiful school, but I just couldn't. I am going to a friend's birthday that will happen to be on December 8.At the end of next month, so I will fly back to New York. I really feel sorry to lose this good chance to enjoy myself with you.
Best wishes.
Yours sincerely,
John
希望陆毁局余闷能帮到你 O(∩_∩早让)O~