Every day some people are killed while they are crossing the roads. Most of these people are old and children. Old people are often killed because they can't see or hear very well. Children are killed because they are not careful. They forget to look and listen before they cross the roads.A car or a bus can't stop quickly. If a car is going very fast, it will travel many meters before it stops. Some people don't always understand this. They think a car can stop in a few meters. It is difficult to know how fast a car is moving. The only way to cross the roads safely is to look both ways, right and left. Then if the roads are empty, you can cross them. Most of the people killed in road accidents are ______.