Three days ago, I went to my college. I got on the bus and sat near a window. Later, the bus stopped on a traffic light. I looked out through the window. Then I saw an old man was crossing the road. There wasn't any policeman there. A boy was coming and he was riding his bike very quickly. He did not see the light or the old man. He kept riding. When he saw the old man, he tried to slow down his bike. But it was too late. He knocked the old man down heavily. The boy also fell down and his head touched the road. His helmet (头盔)was broken but his head wasn't hurt seriously. Both of them couldn't get up. A larger crowd of people came around and someone tried to help, but no one did any useful job. The road was so crowded. At that time I heard the sound of an ambulance (救护车). Then I saw some doctors take them to hospital.

The next day, I read the newspaper and it said that the old man died on the way to the hospital. The boy was saved in time. I was sad. We all know that we can stop some accidents (事故) from happening if we follow the traffic rules.