billiard ball problem

例句：

1. 1. The billiards room is always crowded with players.
   台球室总是挤满了玩家。
2. 2.The problem of how to improve the performance of billiards has not been solved yet.
   如何提高台球性能的问题尚未解决。
3. 3.Billiards is a popular game in many countries.
   台球是一种在许多国家都很受欢迎的游戏。