boundary plane

例句：

1. 1. The boundary plane between two countries is often a contentious issue.
   两个国家之间的边界是经常争议的议题。
2. 2.The engineer used a boundary plane to accurately measure the distance between the two points.
   工程师使用一个边界平面来准确地测量两点之间的距离。
3. 3.The boundary plane was carefully marked on the map to indicate the location of the border.
   地图上小心地标出了边界平面，以指示边境的位置。