So you're back from London, Nancy.
Yes, I had a special dinner there.
Oh? How special? Can you tell me about it?
OK. We had dinner with my old friend Smith. He is an officer in London. When we arrived at the dining hall, all the lights went out. At that time I was a little angry. But then a waiter gave us an explanation, and we laughed.
Why did the lights go out?
Because it's a restaurant for the blind.