内容主要包括:1. 自我介绍(包括英语能力);2. 参加意图(介绍中国、了解其他国家);3. 希望获准。
注意:1. 数100左右;2. 可以适当增加细节，以使行文连贯;3. 邮件开头和结尾已为你写好.
Dear Sir or Madam,
I'm Li Hua, a middle school student from China. I read the announcement of the summer camp that you have posted on the Internet and I am interested in it.
I know that you welcome students from different countries and I'd like to take part in it. I've been learning English for 10 years, and I speak fluent English. What is more, I'll be able to tell students from other countries about China and learn about their countries as well. I hope I will be accepted as a member of your summer camp.
Looking forward to your reply!