假如你是李华，你的外国笔友Jim对中国长城很感兴趣。请你给他根据以下要点给他写一封信，简要介绍长城的一些情况。
历史：有两千多年的历史。
特点：世界上最长的城墙，长6000多千米；建筑材料主要为石头、砖头，修建工作都是人工进行；主要用于防御外来入侵者（invader），沿墙每隔几百米就有烽火台（watchtower）。
现状：世界著名旅游景点之一，每年吸引许多国内外游客到长城观光旅游。
（1）注意：词数80左右；
（2）可适当增加细节，以使行文连贯；
（3）信的开头和结尾已给出，不计入总词数。
Dear Jim，
    Learning that you show great interest in the Great Wall，I'm writing to share some information with you.
______________
Yours sincerely，
Li Hua

【考点】书信类．

【答案】Dear Jim，
Learning that you show great interest in the Great Wall，I'm writing to share some information with you.
The Great Wall，which is more than 6，000 kilometers long，is the longest wall in the world.With a history of over 2，000 years，it was made of stones and bricks.Besides，almost all the construction was done by hand without any machine.As the wall was built to defend the country against foreign invaders，there were watchtowers every few hundred meters along the wall.Now，the Great wall is one of the most famous places of interest in China，attracting many tourists from home and abroad every year.
As is described above，I believe it is worthwhile to pay a visit to the Great Wall.
Yours，
Li hua