horseshoe electromagnet

例句：

1. 1.The horseshoe electromagnet is a useful tool for measuring distances.
   马蹄形电磁铁是一种测量距离的有用工具。
2. 2.The horseshoe electromagnet was used to detect the presence of metal objects in the room.
   马蹄形电磁铁被用来检测房间里金属物体的存在。
3. 3. The horseshoe electromagnet was used to control the flow of electricity.
   马蹄形电磁铁被用来控制电流的流动。