Once there was a famous English painter. His name was Peter. He was asked to paint some pictures on the walls of the king’s palace. With the help of a worker, Peter started painting on the platform (平台). They worked for a whole year and at last the pictures were ready. Peter was happy when he looked at the pictures, because they were really beautiful. He looked at them for a long time, and then took one step back and looked again. Now the pictures were even more beautiful. He took another step, then another. Finally he was at the very edge (边缘) of the platform. But he did not know it, because he was thinking of his pictures. The worker saw everything. "What should I do" he thought. "Peter is at the very edge of the platform. If I cry out, he will take another step, fall off it and surely be killed." So the worker quickly took some paint and threw it at the picture. "What are you doing" shouted the painter, running quickly to his pictures. What was Peter asked to do