violin是可数名词吗

　　The piece is scored for violin, viola and cello.

　　这个乐谱是为小提琴、中提琴和大提琴演奏而编的。

　　It takes a lot of practice to play the violin well.

　　拉好小提琴需要多加练习。

　　A performer plays classical selections on the violin.

　　一位表演者用小提琴演奏古典音乐选段。