None. The light bulb shall never burn out. (OK. It's more cathartic than funny...)
The telephone rang while she was ironing.
Arfson
Just one. He holds up the bulb and waits for the world to revolve around him.
They don't care, as long as they do it better than people from Devon.
Just one. They hold it in place while the world revolves around them.
Two, one to hold the bulb and one to rotate the universe.
