frustum of parabola

例句：

1. 1. The frustum of the cone is its pointed end.
   圆锥的截头部分是它的尖锐端。
2. 2.The frustum of the cone is the part that points upward.
   圆锥的截头部分是向上指向的部分。
3. 3.The frustum of the cone is a small triangular projection at the top of the cone.
   圆锥的截头部分是一个圆锥顶部的小三角形突起。