介绍首都北京
请你阅读你的加拿大网友Tommy的e-mail，根据e-mail的内容，给他写一封回信.
Dear Li Lei,
I haven't heard from you for a long time. I'm glad to tell you that I'll visit Beijing this summer vacation. It is said that Beijing is a great city with a long history and more changes have taken place since the 2008 Olympic Games. I would like to know something about Beijing, such as places of interest, the environment, traffic and people there.
I'm lo
