nodal region

例句：

1. 1. The nodal points of the graph are the intersections of lines.
   图中的节点是线段的交点。
2. 2.The nodal point of the system is the point where the flow changes direction.
   系统的节点是流量改变方向的地方。
3. 3.The nodal region is a small area with high concentrations of pollutants.
   节点区域是一个高浓度污染物的小区域。