这个几何图形是平面的，没有深度。

This geometric shape is ___planar and has no depth.

如果图的边在平面上绘制时不交叉，我们就称它为平面图。

A graph is called ___planar if its edges can be drawn on a flat surface without crossing each other.

甲醛分子具有平面结构，所有原子都位于同一平面上。

The formaldehyde molecule has a ___planar geometry with all atoms lying in the same plane.