mid-plane of the toroid

例句：

1. 1.The engineer used a mid-plane to level the floor.
   工程师使用一个中平面来平整地板。
2. 2.The construction crew was working on the mid-plane of the building.
   建筑工人正在施工大楼的中层平面。
3. 3.The mid-plane of the bridge is crucial for its stability.
   桥梁的中层平面对于其稳定性至关重要。