Now go through TEXT H quickly to answer question 55 and 56.
　
America on Wheels
　
Early automobiles were sometimes only "horseless carriages" powered by gasoline or steam engines. Some of them were so noisy that cities often made laws forbidding their use because they frightened horses.
　
Many countries helped to develop the automobiles. The internal-combustion engine was required in Austria, and France was an early leader in automobile manufacturing. But it was in the United States after 1900 that the automobiles was improved most rapidly. As a large and growing country, the United States needed cars and trucks transportation in places not served by trains.
　
Two brilliant ideas made possible the mass production of automobiles. An American inventor named Eli Whitney thought of one of them, which is known as "standardization of parts." In an effort to speed up production in his gun factory, Whitney decided that each part of a gun could be made by machines so that it would be exactly like all the others of its kind. For example, each trigger would be exactly like all other triggers. A broken trigger could then be replaced immediately by an identical one. After Whitney's idea was applied to automobile production, each part no longer had to be made by hand. Machines were developed that could produce hundreds, even thousands, of identical parts that would fit into place easily and quickly.
　
Another American, Henry Ford, developed the idea of the assembly line. Before Ford introduced the assembly line, each car was built by hand. Such a process was, of course, very slow. As a result, automobiles were so expensive that only rich people could afford them. Ford proposed a system in which each worker would have a special job to do. One person for example, would make only a portion of the wheels. Another would place the wheels on the car. And still another would insert the bolts that held the wheels to the car. Each worker needed to learn only one or two routine tasks.
　
But the really important part of Ford's idea was to bring the work to the worker. An automobile frame, which looks like a steel skeleton, was put on a moving platform. As the frame moved past the workers, each worker could attach a single part. When the car reached the end of the line, it was completely assembled. Oil, gasoline, and water were added, and the car was ready to be driven away. With the increased production made possible by the assembly line, automobiles became much cheaper, and more people were able to afford them.
　
Today it can be said that wheels rum America. The four rubber tires of the automobile move America through work and play. Wheels spin, and people drive off to their jobs. Tires turn, and people shop for the week's food at the big supermarket down the highway. Hubcaps whirl, and the whole family spends a day at the lake. Each year more wheels crowd the highways as 10 million new cars roll out of the factories. One out of every six American works at assembling cars, driving trucks, building roads, or pumping gas. America without cars? It's unthinkable.
　
But even though the majority of Americans would find it hard to imagine what life could be like without a car, some have begun to realize that the automobile is a mixed blessing. Traffic accidents are increasing steadily, and large cities are plagued by traffic congestion. Worst of all, perhaps, is the air pollution caused by the internal-combustion engine. Every car engine burns hundreds of gallons of fuel each year and pumps hundreds of pounds of carbon monoxide and other gases into the air. These gases are one source of the smog that hangs over large cities. Some of these gases are poisonous and dangerous to health, especially for someone with a weak heart or a respiratory disease.
　
One answer to the problem of air pollution is to build a car that does not pollute. That's what several major automobile manufacturers are trying to do. But building a clean car is easier said than done. So far, progress has been slow. Another solution is to eliminate car fumes altogether by getting rid of the internal-combustion engine. Inventors are now working on turbine-powered cars, as well as on cars powered by steam and electricity. But most of us won't be driving cars run on batteries on boiling water for a while yet. Many auto makers believe that it will take years to develop practical models that are powered by electricity or steam.
　
To rid the world of pollution -- pollution caused not just by cars, but by all of modern industrial life -- many people believe we must make some fundamental changes in the way many of us live. Americans may, for example, have to cut down on the number of privately owned cars and depend more on public mass transit systems. Certainly the extensive use of new transit systems could cut down on traffic congestion and air pollution. But these changes do not come easily. Sometimes they clash head on with other urgent problems. For example, if a factory closes down because it cannot meet government pollution standards, a large number of workers suddenly find themselves without jobs. Questioning the quality of the air they breathe becomes less important than worrying about the next paycheck.
　
But drastic action must be taken if we are to reduce traffic accidents, traffic congestion, and air pollution. While wheels have brought better and more convenient transportation, they have also brought new and unforeseen problems. Progress, it turned out, has more than one face.　
　
TEXT I

First read the question.

57. The writer gives us suggestions on ____.
A. how to relax in a crowd
B. how to present oneself before a crowd
C. how to tackle touchy problems in stressful situations
D. how to establish good relationship with strangers
正确答案是