frustum of pyramid

例句：

1. 1.The car's frustum is a perfect fit for the door handle.
   这辆车的凸出部分完美地适合门把手。
2. 2.The scientist found an unusual frustum in the rock formation.
   科学家在岩石构造中发现了一块不寻常的凸出部分。
3. 3.The engineer designed a new frustum that would increase efficiency.
   工程师设计了一个新的凸出部分，以提高效率。