Scientists are trying to make some small cars that may some day take the place of today's big cars. If everyone drives such cars in the future, there will be 1 pollution in the air. There will2be more space or parking cars in cities, and the 3 will be less crowded. Three such cars can fit in4 that it is now needed for one car of the usual size.
The little cars will 5much less to own and to drive. Driving will be 6, too, as these little cars can go only 65 kilometers per hour. The little cars of 7will be fine or getting out of the city, but they will not be useful for8trips. Little cars which are powered by gasoline( 汽油 ) will go 450 kilometers9needing to stop for more gasoline .
If big cars still are used together with the small ones, 10sets of roads will be needed in the future. Some roads will be used for the big, fast cars, and some roads will be needed for the slower, small ones.
