ballstone

例句：

1. 1. The ballstone was smooth and polished to perfection.
   这块球石光滑且打磨得完美无瑕。
2. 2.The old man loved to collect ballstones from the beach.
   这位老人喜欢从海滩上收集球石。
3. 3.The ballstone is a symbol of strength and resilience.
   这块球石象征着力量和韧性。