Q: Read the following article and answer the question. Article: A mother wanted to encourage her son's progress at the piano. She bought tickets to a performance by a great pianist. When the evening arrived,they found their seats near the front of the concert hall and looked at the big piano waiting on the stage. Soon the mother found a friend to talk to,and the boy slipped away. At 8 o'clock,the lights in the hall became weak. The spotlights came on. Only then did they notice the boy up on the piano bench,playing Twinkle,Twinkle Little Star. His mother was shocked,but before she could get her son back,the master himself was 0n the stage and quickly moving to the piano. He went up to the boy and said gently,"Don't stop. Keep playing. "Then he leaned over and reached down with his left hand and began filling in the bass part. Soon his fight arm reached around the other side and played a delightful piece of music. Together,the old master and the little boy carried the crowd away with their beautiful music. In all our lives,we receive helping hands--some we notice,some we don't. Equally we ourselves have a great many chances to give a helping hand to others--sometimes we like our help to be noticed,sometimes we don't. Little of what we a11 achieve comes without learning or support from others. What we receive we should give back. Question: The little boy slipped onto the stage when_. Answer:
A:
her mother talked to her friend