Today's topic is a very popular form of music in the United States called " bluegrass" .

今天的话题是在美国非常流行的一种音乐形式，叫做“蓝草”。

Now rock is one of the most popular forms of music in the world and its fans can be seen from Beijing to Boston and all the places in between.

现代摇滚成为了世界上最流行的音乐之一，它的歌迷遍及从北京到波士顿以及中间的所有地方。