假设你是 Vivian，你正在北京旅行．请根据下列信息提示，给你的好友 Mark 写一封 80 词左右的信件，描述一下你的北京之旅．信件的开头和结尾已给出，不计入总词数．

My experience in Beijing
How long	Five days
Things I have done here	Visit the Summer Palace，climb the Great Wall，try Beijing Duck
Things I haven′t done here	Visit the h ut    o  n  g  s in Beijing，go to the Beijing Zoo
How I feel about it	Great，tired but happy

Dear Mark，
Have you ever been to Beijing？Now I′m having a wonderful time in Beijing．
                                  

Yours，Vivian．