Originally posted by gonnawhoopyourassYou can't.
There is a room without any windows, with 3 lightbulbs on the ceiling, each lightbulb can be put on or off with a switch. But the 3 switches are outside the room.
You will have to find out which switch is connected with which lightbulb, but you can only use the switches while the door is closed, further more you may only open the door only once.
How can you make sure which switch is for witch lightbulb?