second knuckle

例句：

1. 1. He was so focused on his work that he forgot to eat.
   他太专注于工作了，以至于忘了吃饭。
2. 2.The dancer's second knuckle is the most important part of her routine.
   舞者的第二个指关节是她舞蹈中最重要的部分。
3. 3. When she picked up her pen, she accidentally scratched her second knuckle.
   当她拿起笔时，她不小心划伤了第二个指关节。