题目内容：

Some years ago industries had more freedom than they have now，and they did not need to be as careful as they must today. They did not need to worry a lot about the safety of the new products that they developed. They did not have to pay much attention to the health and safety of the people who worked for them. Often new products were dangerous for the people who used them; often conditions in the work place had very bad effects on the health of the workers.

Of course sometimes there were real disasters which attracted the attention of governments and which showed the need for changes. Also scientists who were doing research into the health of workers sometimes produced information which governments could not ignore. At such times, there were inquiries into the causes of the disasters or the problems. New safety rules were often introduced as a result of these inquiries; however, the new rules came too late to protect the people who died or who became seriously ill.

Today many governments have special departments which protect customers and workers. In the U.S., for example, there is a department which tests new airplanes and gives warnings about possible problems. It also makes the rules that aircraft producers must follow. Another department controls the foods and drugs that companies sell. A third department looks at the places where people work, and then reports any companies that are breaking the laws which protect the health and safety of workers. Of course, new government departments and new laws cannot prevent every accident or illness, but they are having some good results. Our work places are safer and cleaner than before. The planes and cars which we use for travel are better. Producers are thinking more about the safety and health of the people who buy and use their products.

51. The main topic of the passage is ______.

A. conditions in the work place            B. the freedom of industries in the past

C. changes in industrial production       D. the safety and health of workers and customers

52. It can be inferred from the passage that in the past ______.

A. workers often got ill because of the poor working conditions

B. companies were free to put out any products they wanted to

C. many people were killed by dangerous products

D. industries were as careful in management as they are today

53. It is implied in the passage that ______.

A. governments and companies had different opinions about the safety of products

B. in the past no safety laws were introduced by governments

C. government officials often did not listen to scientists

D. governments paid no attention to the safety of products at all

54. From the passage, we know that some years ago safety rules ______.

A. were put forward due to scientists’ recommendations

B. came into being as a result of the workers’ demands

C. were introduced because quite a number of people were killed or seriously injured

D. were effective enough to protect workers and customers

55. The special departments protect customers and workers in many ways EXCEPT by ______.

A. testing new products                       B. controlling the sale of products

C. designing new products                   D. inspecting work places