joints of hand

例句：

1. 1.The doctor examined the patient's joints carefully.
   医生仔细检查了患者的关节。
2. 2.Joint pain is a common symptom of arthritis.
   关节疼痛是关节炎的常见症状。
3. 3.The scientist discovered a new method to join two pieces of metal together.
   科学家发现了一种将两块金属连接在一起的新方法。