骨节

例句：

1. 1. The old man's arthritis made it difficult for him to walk.
   老人的关节炎让他很难走路。
2. 2. The dancer's flexibility is remarkable, as she can move her arms and legs in a way thatseems almost magical.
   舞者的灵活性令人惊叹，她的动作似乎带有魔法般的魔力。
3. 3.The scientist studied the structure of the human skeleton to understand its function.
   科学家研究了人类骨骼的结构，以了解其功能。