单选题 Scientists now tend to agree that the noise level for potential hearing loss begins at about 70 decibels. Some of them are very concerned because normal daily life often exposes people to noise levels of about 70 decibels even inside their homes. Cities have always been noisy, but noise is now spreading to areas that were quiet just a few years ago.
Clearly, something must be done or noise will seriously and permanently maim the population. Fortunately, the knowledge and methods to control noise already exist. As a matter of fact, this is one instance where the knowledge of control methods exceeds the knowledge about the effects on human life and on the environment.
There are two common means for control. The first is reducing noise at its source, and the second is changing the sound path by distance or by shielding.
The second approach is being used more often today as people become more aware of the danger of noise. New building codes require better sound insulation in homes and apartments. More and more towns are passing zoning ordinances that try to segregate noisy factories or airports from residential areas. Sound-absorbent materials and construction designed to block sound paths are slowly coming into use in offices and homes. New highways are being built to redirect traffic noise up and away from nearby areas. Aircraft are increasingly being required to use reduced power flights around airports.
There are many examples of available noise control methods that are not being used. More flexible building codes would permit the use of quieter kinds of plumbing pipes. Sound-absorbing materials can reduce the noise of motors and engines. Power generators can be quieted with baffles, exhaust silencers, and sound absorbers. Truck tires can be made with quieter treads. In many cases, the cost of building quieter machines is the same or only slightly higher than that of the current noisy ones. Even though the new equipment may cost more initially, it can prove more profitable in the long run. The new jumbo jets, for example, are quieter than the older ones, yet they are more powerful and carry twice as many passengers. All of these methods are only partial measures as noisy levels continue to rise. Most specialists in the field agree that much of the solution must come from eliminating some of the noise at its source, therefore saving through prevention the large costs of hearing loss.
单选题 The noise level for possible bearing loss begins at about ______.
  • A. 30 decibels
  • B. 75 decibels
  • C. 100 decibels
  • D. none of the above
【正确答案】 D
【答案解析】[解析] 题目问：噪音达到什么水平就可能导致听力丧失？第一段第一句“the noise level for potential hearing loss begins at about 70 decibels.”通过这句话可知，噪音达到70分贝就可以造成潜在听力丧失。据此判断，应选择D。
单选题 Jet pilots are being advised to land ______.
  • A. on longer runways
  • B. from nearby areas
  • C. after dark
  • D. with reduced power
【正确答案】 D
【答案解析】[解析] 题目问：为什么说喷气飞行员是明智的？第四段最后一句“Aircraft are increasingly being required to use reduced power flights around airports”，通过这句话可知，在机场周围飞行的飞机正在被要求降低功耗。据此判断，应选挥D。
单选题 How many practical means for controlling noise does the author present?
  • A. one
  • B. two
  • C. three
  • D. four
【正确答案】 B
【答案解析】[解析] 题目问；作者介绍了集中控制噪音的方法？第三段“There are two common means for control”，通过这句话可知，关于控制噪音有两个常规的途径。据此判断，应选择B。
单选题 The reader can assume that airport of the future will ______.
  • A. have runways in a north-south pattern
  • B. be located in unpopulated areas
  • C. be required to warn passengers of high noise levels
  • D. in nearby areas
【正确答案】 B
【答案解析】[解析] 题目问：读者可以猜想未来的机场会怎样？第四段第三句“More and more towns are passing zoning ordinances that try to segregate noisy factories or airports from residential areas.”通过这句话可知，将居民区与噪音污染严重的工厂和机场分开，是很好的控制噪音手段。据此判断，应选择B。
单选题 Jumbo jets are mentioned as examples of ______.
  • A. efficient transportation with low levels of noise
  • B. vehicles that cause serious air pollution
  • C. scientific advances that do more harm than good
  • D. quieter and older vehicle
【正确答案】 A
【答案解析】[解析] 题目问：大型喷气式飞机是作为什么例子出现的？第五段最后一句“The new jumbo jets...they are more powerful and carry twice as many passengers.”通过这句话可知，新式的大型喷气机效率更高，并且能够装载更多的旅客。据此判断，应选择A。