Kate, don't forget to turn off the light when you leave the room.

凯特，你离开房间时别忘了关灯。

youdao

Please turn the light off before leaving the room.

离开房间前，请把灯关掉。

youdao

Please turn off the light when you leave the room。

离屋时请关灯。

youdao

He could turn off a light and then jump into his bed before the room got dark.

VOA: special.2009.01.24

Users would be able to program lights to automatically turn on and off when people are in the room, to adjust light levels to the amount of daylight coming into a room and to turn on and off or dim at different times via the Internet.

FORBES: New Partnership Aims To Make LEDs Cost Competitive