concave flank cam

例句：

1. 1.The concave of the rock is smooth and shiny.
   岩石的凹处光滑且有光泽。
2. 2. The car's dashboard is designed with a concave center console.
   汽车仪表盘设计有凹中心的中控台。
3. 3.The concave of the bowl is perfect for holding small items.
   碗的凹面非常适合放置小物品。