dual frequency electric locomotive

例句：

1. 1.The dual-frequency electric locomotive is an essential tool for railway maintenance.
   双频电力机车是铁路维护中不可或缺的工具。
2. 2.The dual-frequency electric locomotive has greatly improved the efficiency of railway operations.
   双频电力机车大大提高了铁路运营的效率。
3. 3.The dual-frequency electric locomotive is used to transport passengers and goods across long distances.
   双频电力机车用于长途运输乘客和货物。