A mother wanted to encourage her son to play the piano. She bought tickets to the concert of a great pianist. When they arrived at the theater, the mother found a friend. Sbe stopped to talk to ber friend and her son ran off. At eight o'clock'the lights began to dim ,and the concert was set to start. The mother began to look for the boy. Then, she saw her 6-year-old son on stage. He was on the piano bench playing Twinkle, Twinkle little star. The mother was very shocked. Before she could get her son back, the famous pianist  himself was on the stage and quickly moved to the piano. "Don't stop. Keep playing," he said kindly to the boy. The great pianist reached down with his left hand and began filling in the bass  of the song. Soon, his right arm reached around the other side and played a beautiful piece of music. Together, the two impressed   people with their beautiful music. In all of our lives, we receive helping hands- some we notice, some we don't. We also have Iots of chances to give helping hands- sometimes we want people to know, sometimes we don't. Little of what we all achieve comes without other's help. What we receive we should give back The mother took her son to the piano concert because  _  .
her friend sent them two tickets the pianist invited them there she wanted to develop his interest in piano her son liked the pianist very much