单选题
Once there was a man who had two children, a boy and a girl. The boy was good looking, but the girl was not. One day they found a mirror and for the first time, they saw what they looked like. The boy was very pleased. He said to his sister, "How handsome I am! I look much nicer than you? The girl did not like what he said. She gave her brother a push and said, "Go away!" Their father saw what was happening and said to the boy. "You must always be as good as you look." And to the gift he said, "My dear, if you help everyone and be kind to everyone, you will be loved. Our looks don't mean anything./
单选题
The boy and the girl didn't know what they looked like until ______.