假设你是李明，你的美国笔友汤姆想了解中国的名胜古迹。请你根据以下提示，给汤姆回封邮件，向他介绍一下我国的万里长城。How old is it? Why did people build it? How long is it? … 要求：语句通顺、自然，意思连贯，层次分明；可以根据提示自由发挥；110 词左右。开头和结尾已给出，不计入总词数。

Dear Tom,

    How are you? You said you would like to know about some places of interest in China. Let me tell you something about the Great Wall.

    Welcome to China and enjoy it one day!

Yours,

Li Ming