Dear Marry,
Greetings! Or should I say ni hao? I have just been back from the summer camp. And I'd much appreciate your help in the summer camp. I could not possiblely enjoy the time without you. You are always a great friend. By the way, I could still remember that you showed a great interest in Chinese culture. So I would like to invite you to China next year during the summer holiday .I gurantee that I will, myself give you a wonderfull tour throughout the rich historical and cultural preserve of China. Current cultures are of course not to be missed, so you may visit my school if you wish and I will introduce you to all my friends and teachers. Finally, if you are any interested, please mail back. Then we will discuss about the travel further.
Yours 【你的名字】