假如你是李华，你校即将举行一年一度的“校园书市 (a campus book fair)”活动，其目的是给同学们提供一个交换、利用图书的机会。请你用英语写信给你的加拿大笔友Mike, 介绍此次活动的有关情况。内容应包括：
1）活动目的；
2）活动内容：买书，卖书，交换图书;
3）活动意义。
Dear Mike,
How are you doing these days?
……
Yours,
Li Hua
Dear Mike,
How are you doing these days?
Aimed at providing a platform where students can have a chance to exchange and make use of their books, the annual campus book fair will soon be held in our school. The fair will attract a huge cro
