One afternoon in January in 1998, Susan Sharp, 43, and her 8-year-old son David, were walking across an icy square, when Susan's cane(手杖) slipped on the ice. Her face   36   first into the mud. David   37   her mother's side, “Are you all right, Mom”   38  , Susan pulled herself up, “I'm okay, Honey,” she said.

Susan was falling more   39   since she had trouble walking. Every inch of ice was a   40   danger for her. “I wish I could do something,” the boy thought. David, too, was having   41   of his own. The boy had a speech problem, so at school he talked   42  .

　　One day, David's teacher announced a   43   homework. "Each of you is going to come up with an   44  ," she said. This was for "INVENT AMERICA", a national competition to encourage creativity in children.

　　An idea   45   David one evening. If only his mother's cane didn't slip on the ice. “What if I   46   your cane to a nail coming out of the bottom” he asked his mother.

　　“   47   the sharp end would scratch(划破) floors,” Susan said.

　　“No, Mom, I   48   make it like a ball-point pen. You take your hand off the button and the   49   returns back up.” Hours later the cane was finished. David and his father   50   as Susan used it to walk 50 feet about the   51  . Happily Susan cried out, “It   52   !”

　　In July 1999, David was  53   national winner for the "INVENT AMERICA". David began to make public appearance. Thus he was forced to communicate  54  .Today, David is nearly free of his speech problem, and his   55   is becoming well accepted.