Dear Sir or Madam：
亲爱的女士或者先生：
Thank you for taking your time to read my letter. As the coming of the International Trade Exposition I’d like very much to be a volunteer。
谢谢你抽出时间来阅读我的信。对于即将到来的国际贸易博览会，我非常想成为一名志愿者。
All our citizens are hosts for this special event. Above all I promise I should endeavor to serve with enthusiasm our distinguished guests from all over the world. Besides I have a rich knowledge about Chinese history so I will be not only a servant but also a carrier for our splendid culture. What’s more as we all know English as an international language will play an important role in communication during the Exposition and I am good at it. I can express myself fluently and clearly in English。
我们所有的公民都是这个特殊事件的主人。首先，我保证我会努力与热情服务我们尊贵的来自世界各地的客人。另外，我拥有丰富的中国历史知识，所以我将不仅仅是一个仆人，也是一个中国灿烂文化的载体。更重要的是，我们都知道，英语作为一种国际语言，将在通信中发挥重要的作用，在本次展会上，我很擅长。我能用英语流利清晰地表达。
To sum up I believe I can be a qualified volunteer. I will value it and do all I can if I could be accepted to be one.
总之，我相信我能成为一个合格的志愿者。我会珍惜它，如果我可以成为其中的一个，我一定会尽我所能。
Yours