the concert began with a piece by an unknown composer 求整句翻译,还有其中的a piece,

the concert began with a piece by an unknown composer 求整句翻译,还有其中的a piece,

音乐会伴着一首不知名的作曲家的曲子开始了.
a piece是之一首曲子.是a piece of music 的缩写