dynamo geomagnetic theory

例句：

1. 1. The dynamos are responsible for powering the city's subway system.
   这些发电机负责为城市的地铁系统提供动力。
2. 2. The engineer used a dynamometer to measure the strength of the material.
   工程师使用测力计来测量材料的强度。
3. 3. The dynamos were designed to be energy efficient and environmentally friendly.
   这些发电机被设计成能源效率高且环保。