三面体

例句：

1. 1. The cube is a three-dimensional shape with six faces.
   立方体是一种有三个面的立体形状。
2. 2. The triangular prism has a unique structure that makes it easy to stack.
   这个三棱柱有一个独特的结构，使得它容易堆叠。
3. 3. The triangular pyramid is a common building material used in ancient architecture.
   三角形金字塔是古代建筑中常用的建筑材料。