假定你是李华。近日有网友在推特贴出了中国大妈带领美国大妈在新泽西大跳广场舞的照片，你的美国朋友David看过后，很想了解中国流行的广场舞（square dance）的相关情况。请你用英语给他写封回信，要点包括： 1)广场舞跳的时间、地点、参与人员等； 2)广场舞流行的原因； 3)广场舞的缺点。 

注意： 1)词数100左右； 2)可以适当增加细节，以使行文连贯； 3)开头语和结束语已为你写好。 

Dear David， 

I am writing to tell you something about the square dance in China. 

Yours, 

LiHua  

范文： 

Dear David, 

I am writing to tell you something about the square dance in China. In the morning or after dinner, people, especially elderly women, will gather in squares to dance to popular music. More and more young people are also joining in now.     

There are many reasons behind its popularity. First of all,China has made great progress in its social and economical development in the past decades, and people have more time and energy to enjoy themselves. Besides,doing the square dance is a good way for people to keep fit. 

However, just as each coin has two sides,this kind of dance has also leads to some problems. For example, dancers play loud music and occupy lots of public places, which annoy many other people.Maybe square dancers need to make some changes. 

Yours, 

Li Hua