You want to know where the safest place for young children is in the car? Experts all say the back seat is the safest place for a child of any age. In the back seat, the child is farthest away from the force or effect of a head-on collision (迎头撞击) , which can cause the most injuries. Just as important, the child in the back seat is removed from the passenger airbag, if there is any. If your child is under eight years of age and weighs more than 80 pounds, it is necessary to fit your car with a special child-safety seat. The child-safety seat comes in three types or sizes: The first type is designed for babies from birth to one year of age, until the baby weighs about 20 pounds; the second size is for children between one and four years of age, who weigh between 20 and 40 pounds; the third kind is used by older children big enough to use the car's belt system. Moreover, all these safety seats must be fitted and held in place on the car's back seat. If your child does need your attention while. you are driving, don't look back with only one hand on the wheel. Just pull over. This text mainly discusses ______.