节约用电

• save on electricity
• economize on electricity

例句

1. 告诉孩子在离开房间时关掉所有的灯，以节约用电。
   Tell the boy to switch off all lights as he leaves the room, to save electricity.
2. 总统关于节约用电的讲话被接受了，人们开始做`到人离灯灭了。
   The president's speech about the need for saving power got home, and everyone started turning off lights.