main source of electric power的用法和樣例：
例句
- Turn on the main source switch, and the Control Unit is now put in work.
打開(kāi)主電源開(kāi)關(guān)時(shí)控制部件將開(kāi)始工作。 - Three-phase UPS systems are used in most large data centers for power conditioning and battery back-up in the event of mains power failure.
當數據中心一旦發(fā)生主電源掉電的時(shí)候，三相不間斷電源系統是應用最廣泛的后備電池和供電條件。
