内弧面

例句：

1. 1. The car'sinner arc surface is smooth and shiny.
   这辆车的内弧面光滑且有光泽。
2. 2. The inner arc surface ofthe gear is designed to reduce friction.
   齿轮的内弧面设计来减少摩擦。
3. 3.The inner arc surface of the bladeis sharp enough to cut through even thethickest material.
   刀片的内弧面足够锋利，可以切割最厚的材料。