A
The United States is full of cars. There are still many families without cars, but some families have two or more. However, cars are used for more than pleasure. They are a necessary part of life.
Cars are used for business. They are driven to offices and factories by workers who have no other way to get to their jobs. When salesmen are sent to different parts of the city, they have to drive in order to carry their products. Farmers have to drive into the city in order to get supplies.
Sometimes small children must be driven to school. In some cities school buses are used only when children live more than a mile away from the school. When the children are too young to walk too far, their mothers take turns driving them to school. One mother drives on Mondays taking her own children and the neighbours' as well. Another mother drives on Tuesdays, another on Wednesday, and so on. This is called forming a car pool（拼车）. Men also form car pools, with three or four men taking turns driving to the place where they all work.
More car pools should be formed in order to put fewer cars on the road and use less gas. Too many cars are being driven. Something will have to be done about the use of cars.
21．The United States is filled with cars, but ______ .
A．not every family has a car B. few families have two cars or even more
C．every family has a car D．every American has a car
22．What's the main idea of the second paragraph?
A．Salesmen drive to carry their products B. Workers drive cars to offices and factories
C．Farmers drive into cities to get supplies D．Cars are widely used
23．Mot hers form car pools in order that________ .
A．they can drive to school
B．they can take turns driving their children to school
C．they reach school quickly
D．they can drive their children to school in time
24．The traffic in and around cities is a great problem because_________ .
A．people put fewer cars on the roads B．there are too many car pools
C．there is less gas C．too many cars are being driven
