heteropolar D.C. linear motor

例句：

1. 1. The design of the heteropolar D.C. linear motor is highly efficient and energy-saving.
   异极直流线性电机的设计非常高效且节能。
2. 2. The development of this type of motor has greatly improved our transportation efficiency.
   这种电机的开发大大提高了我们的运输效率。
3. 3.In recent years, scientists have been exploring the application of heteropolar D.C. linear motors in various fields.
   近年来，科学家们一直在探索异极直流线性电机在各个领域的应用。