离开时别忘了关灯怎么说？（用英语） 谢谢啊、快点哈。时间一去不等人啊、

Don`t forget to turn off the light when you leave

Don't forget to turn off the light when you leave the room.

forget to do sth.忘记做某事（没做，表提醒）
forget doing sth.忘记做某事（做过了，却忘记了）

Please don't forget to take off the lights when you will leave.

Don't forget turn off the light when you're leaving.

Remember to turn off light when you leave.

Please turn off the light when you left