51．Suppose you are driving your friend to the airport and the car radio is on, what can't you hear i——青夏教育精英家教网—

摘要：51．Suppose you are driving your friend to the airport and the car radio is on, what can't you hear if you wear a headphone? A．The radio music and the car engine noise. B．The noise of the planes passing overhead and what your friend says. C．The radio music and what your friend says. D．The nose of the car and the planes passing overhead. D If you boss asks you to work in Moscow this year, he’d better offer you more money to do so - or even double that depending on where you live now. That’s because Moscow has just been found to be the world’s most expensive city for the second year in a row by Mercer Human Resources Consulting. Using the cost of living in New York as a base, Mercer determined Moscow is 34.4 percent more expensive including the cost of housing, transportation, food, clothing, household goods and entertainment. A two-bedroom flat in Moscow now costs $4,000 a month; a CD $24.83, and an international newspaper $6.30, according to Mercer. By comparison, a fast food meal with a hamburgeris a steal at $4.80. London takes the No.2 place, up from No.5 a year ago, thanks to higher cost of housing and a stronger British pound relative to the dollar. Mercer estimatesLondon is 26 percent more expensive than New York these days. Following London closely are Seoul and Tokyo, both of which are 22 percent more expensive than New York, while No.5 Hong Kong is 19 percent more costly. Among North American cities, New York and Los Angeles are the most expensive and are the only two listed in the top 50 of the world’s most expensive cities. But both have fallen since last year’s study - New York came in 15th, down from 10th place, while Los Angeles fell to 42nd from 29th place a year ago. San Francisco came in a distant third at No. 54, down 20 places from a year earlier. Toronto, meanwhile, is Canada’s most expensive city but fell 35 places to take 82nd place worldwide. In Australia, Sydney is the priciest place to live in and No. 21 worldwide.

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Earplugs have been the simple but effective way to stop noise affecting your mind, but their shortcoming is that they also block out sounds you may want or need to hear, such as music or someone talking to you.

The answer to this problem is "active noise cancellation(抵消)"-headphones that are made up of a microphone and electronics(电子装置) that take all background low-frequency (低频率) noise, turn the sound waves upside down and rebroadcast them into your ear.

The result is that all the unwanted noises around are blocked out.

In effect, one set of electronically produced sound wave has sucked away the unwanted sound waves of noise.

Stand next to a busy road wearing the noise cancellation headphones and the traffic noise disappears. Sit in an airplane and the engine noise dies away. In a noisy office, the noise of office equipment, people and air-conditioning is gone. You can still, however, hear music or talk with people because that sound does not have a regular pattern and so the device(装置) does not block it.

81. What is the best way to keep out the unwanted noise?

A. To wear an earplug.

B. To wear a headphone.

C. To wear a microphone.

D. To wear electronics.

82. Which of the following gives a general idea on how the above device works?

A. By producing low-frequency sound waves and rebroadcast them.

B. By producing new sound waves to suck away the unwanted sound waves.

C. By changing all background low-frequency noise into an irregular pattern.

D. By sucking away all the low- frequency sound waves turned upside down.

83. Suppose you are driving your friend to the airport and the car radio is on, what can't you hear if you wear a headphone?

A. The radio music and the car engine noise.

B. The noise of the planes passing overhead and what your friend says.

C. The radio music and what your friend says.

D. The noise of the car and the planes passing overhead.

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A New Headphone

The answer to a very great noise may not be blocking it out with earplugs but taking that noise and bearing it as its own game.

The answer to this problem is “ active noise cancellation(抵消)” headphones that are made up of a microphone and electronics (电子装置)that take all background low-frequency (低频率) noise, turn the sound waves upside down and rebroadcast them into your ears.

The result is that all the unwanted noises around are blocked out.

In effect, one set of electronically produced around wave has sucked away the unwanted sound waves of noise.

Stand next to a busy road wearing the noise cancellation headphones and the traffic noise disappears. Sit in an airplane and the engine noise dies away. In a noisy office, the noise of office equipment, people and air-conditioning is gone. You can still , however, hear music or people talking because that sound does not have a regular pattern and so the device (装置) does not block it.

49．What is the best way to keep out the unwanted noise?

A．To wear an earplug. B．To wear a headphone.

C．To wear a microphone. D．To wear electronics.

50．Which of the following gives a general idea of how the above device works?

A．By producing low-frequency sound waves and rebroadcast them.

B．By producing new sound waves to suck away the unwanted sound waves.

C．By changing all background low-frequency noise into an irregular pattern.

D．By sucking away all the low-frequency sound waves turned upside down.

51．Suppose you are driving your friend to the airport and the car radio is on, what can't you hear if you wear a headphone?

A．The radio music and the car engine noise.

B．The noise of the planes passing overhead and what your friend says.

C．The radio music and what your friend says.

D．The nose of the car and the planes passing overhead.

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