题目内容
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Because of noise outside, Nancy had great difficulty ____________ (集中注意力在实验上).
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更多“Because of noise outside, Nancy had great difficulty ____________ （集中注意力在实验上).”相关的问题
A．focusing
B．carrying out
C．paying for
D．continuing with
To fight a noise by making more noise sounds strange, but that' s exactly what motor engi-neers are doing in Germany and some other countries．
Carmaker' s research and development laboratories have already proved that mixing more noisewith the help of loudspeakers can reduce the unwanted noise．Physicists have known about thetechnique for a long time．Sound is made up of pressure waves in the air．If two sound waves ofthe same frequency(频率) mix so that the highest point of one wave happens at the same time asthe lowest point of the other wave, the result is no sound．Therefore, by producing a perfect copyof the noise and delaying it by half a wave cycle (周期), we can kill the unwanted noise．Usingthis technique many carmakers are racing to develop noise killing systems (系统) both inside andoutside the cars．
Another good thing about the use of noise killing systems is that it saves the need for a silencer;this not only reduces the weight of a car, but also makes the motor burn less fuel and work better．
Some engineers believe that the noise killing system will be used in most cars within a fewyears．But the carmakers haven' t decided if they will carry it into production because it would addseveral hundred dollars to the cost of their cars．
Which of the following gives a general idea of how the noise killing system works？ 查看材料
A.By producing pressure waves going in the opposite direction．
B.By mixing high frequency sound waves with low frequency sound waves．
C.By mixing new sound waves with the noise and sending them out together．
D.By making copies of the unwanted sound waves and letting them out a little later．
D
To fight a noise by making more noise sounds strange, but that ' s exactly what motor engi-
neers are doing in Germany and some other countries.
Carmaker ' s research and development laboratories have already proved that mixing more noise
with the help of loudspeakers can reduce the unwanted noise. Physicists have known about the tech-
nique for a long time. Sound is made up of pressure waves in the air. If two sound waves' of the
same frequency(频率） mix so that the highest point of one wave happens at the same time as the'
lowest point of the other wave, the result is no sound. Therefore, by producing a perfect copy of
the noise and delaying it by half a wave cycle(周期) ,we can kill the unwanted noise. Using this
technique many carmakers are racing to develop noise killing systems(系统) borh inside and outside
the cars.
Another good thing about the use of noise killing systems is that it saves the need for a silencer; this not only reduces the weight of a car, but also makes the motor bum less fuel and work better. Sorpe engineers believe that the noise killing system will be used in most cars within a few
years. But the carmakers haven' t decided if they will carry it into production because it would add several hundred dollars to the cost of their cars.
69. Which of the following gives a general idea of how the noise killing system works？
[ A]By producing pressure waves going in the opposite direction.
[ B ] By mixing high frequency sound waves with .low frequency sound waves.
[C]By mixing new sound waves with the noise and sending them out together.
[D]By making copies of the unwanted sound waves and letting them out a little later.
听力原文： The idea of fighting a noise by making more noise sounds strange, but that's exactly what motor engineers are doing in Germany and some other countries.
Carmaker's research and development laboratories have already proved that mixing in more noise with the help of loudspeakers can reduce the unwanted noise.
Physicists have known about the technique for a long time. Sound is made up of pressure waves in the air. If two sound waves of the same frequency mix so that the highest point of one wave happens at the same time with the lowest point of the other wave, the result is no sound. Therefore, by producing a perfect copy of the noise and delaying it by half a wave cycle, we can kill the unwanted noise. Using this technique many carmakers are racing to develop noise-killing systems both inside and outside the cars.
Another good thing about the use of noise-killing systems is that it saves the need for a silencer, which not only reduces the weight of a car, but also makes the motor burn less oil and work better.
Some engineers believe that the noise-killing system will be used in most cars in 1996. But the carmakers haven't decided if they will put it into production because it would add several hundred dollars to the cost of their cars.
(30)
A．By mixing high frequency sound waves with low frequency sound waves.
B．By producing pressure waves going in the opposite direction.
C．By mixing new sound waves with the noise and sending them out together.
D．By making copies of the unwanted sound waves and letting them out a little later.
Car makers' research and development laboratories have already proved that mixing more noise with the help of loudspeakers can reduce the unwanted noise.
Physicists have known about the technique for a long time. Sound is made up of pressure waves in the air. If two sound waves of the same frequency(频率) mix so that the highest point of one wave happens at the same time as the lowest point of the other wave, the result is no sound. Therefore ,by producing a perfect copy of the noise and delaying it by half a wave cycle(周期), we can kill the unwanted noise. Using this technique many carmakers are racing to develop noise-killing systems(系统)both inside and outside the cars.
Another good thing about the use of noise-killing systems is that it saves the need for a silencer; this not only reduces the weight of a car, but also makes the motor burn less fuel and work better.
Some engineers believe that the noise-killing system will be used in most cars within a few years. But the carmakers haven't decided if they will carry it into production because it would add several hundred dollars to the cost of their cars.
Which of the following gives a general idea of how the noise-killing system works？
A．By producing pressure waves going in the opposite direction.
B．By mixing high frequency sound waves with low frequency sound waves.
C．By mixing new sound waves with the noise and sending them out together.
D．By making copies of the unwanted sound waves and letting them out a little later.
Car makers' research and development laboratories have already proved that mixing in more noise with the help of loudspeaker can reduce the unwanted noise.
Physicists have known about the technique for a long time. Sound is made up of pressure waves in tire air. If two sound waves of the same frequency mix so that the highest point of one wave happens at the same time as the lowest point of the other wave, the result is no sound. Therefore, by producing a perfect copy of the noise and delaying it by half a wave cycle, we can kill the unwanted noise. Using this technique many carmakers are racing to develop noise-killing systems both inside and outside the cars.
Another good thing about the use of noise-killing systems is that it saves the need for a silencer; this not only reduces the weight of a car, but also makes the motor burn less fuel and work better.
Some engineers believe that the noise-killing system will be used in most cars within a few years. But the carmakers haven't decided if they will put it into production because it would add several hundred dollars to the cost of their cars.
Which of the following gives a general idea of how the noise-killing system works？
A．By producing pressure waves going in the opposite direction.
B．By mixing high frequency sound waves with low frequency sound waves.
C．By mixing new sound waves with the noise and sending them out together.
D．By making copies of the unwanted sound waves and letting them out a little later.
听力原文： The tragedy of Titanic will always be remembered, because she went down on her first voyage with heavy loss of life. Titanic, the great ship, sailed for New York from' Southampton on April 10th, 1912. She was carrying 1,316 passengers and a crew of 891.
Four days after setting out, the Titanic was sailing across the icy waters of the North Atlantic. Suddenly a huge iceberg was spotted. After the alarm had been given the great ship turned sharply to avoid a direct collision. The Titanic turned just in time, narrowly missing the immense wall of ice which rose over 100 feet out of the water beside her. Suddenly, there was a slight trembling sound from below. The captain went down to see what had happened. The noise had been so weak that no one thought that the ship had been damaged. The captain realized in horror that the Titanic was sinking rapidly. He ordered to abandon ship. Hundreds of people jumped into the icy water. As there were not enough lifeboats for everybody, 1,500 lives were lost.
(30)
A．1,500.00
B．1,316.00
C．891
D．2,207.00
Then he sat down to think, "I must do something about the noise," he said.He thought and thought.At last he had an idea."Ah, I'll put some cotton in my ears.Then I won't be able to hear the noise." The next day he went to the door of his neighbor, and took hold of the bell.This time he pulled even harder.The bell rang loudly, but the thief did not hear anything.With another hard pull he got the bell out.Just then the neighbor came running out.
"Steal my bell？ I'll teach you a lesson," the angry man shouted.And he hit the thief on the nose.
The foolish thief did not know how the neighbor found out he was stealing the bell."Why did he come out just then？" he wondered.
31.The thief was trying to get his neighbor's doorbell.()
A.T
B.F
32.The thief put some cotton in his ears so as not to hear anything.()
A.T
B.F
33.The neighbor ran out probably because he knew his doorbell was being stolen.()
A.T
B.F
34.The neighbor hit the thief to punish him for stealing.()
A.T
B.F
35.The thief thought the neighbor couldn't hear the noise of the bell.()
A.T
B.F
She sat in her seat, her hands gripping its arms, her seat belt already fastened. The air hostess was talking, telling everyone what to do in case of emergency, showing them where their .life-jackets were. The plane was crowded, every seat was full. From her window seat, getting out in a hurry would be impossible, thought Ann. In any case who would want to get out of a plane in mid-air？
The engines began to shake--the noise increased till it was like a great rushing wind. She looked out to see the runway slip past at astonishing speed. She wanted to cry out--to stop the plane before it left the ground, but she knew she was trapped in this great roaring machine. I must scream, she told herself, and put her hands over her eyes.
There was a strange feeling as if she were going up in a lift. The noise died down. Carefully she opened her eyes. Through the window she saw a great carpet of cloud above, so beautiful that she stared in wonder, hardly turning away from the window till they touched down.
Ann thought she would be frightened because ______.
A．she had never flown before
B．she had a fear of being in high places
C．she hadn' t made proper preparations.
D．she was naturally timid
What bothers noise experts is that plenty of commonplace machines are just as loud as, or even louder than, the Concorde. A sanitation truck can be noisier, and so can a heavy diesel truck pulling away from a stop sign. One expert who has gone out of his way to dramatize the prevalent offensiveness of the city sound-scale is Dr. Thomas H. Fay, director of speech and hearing at Columbia-Presbyterian Medical Center in New York. Dr. Fay took a sound-meter into a New York City subway and proved that an approaching train can be twice as loud as the Concorde.
Since World War Ⅱ, the number of the high-powered noise-makers, from trucks and motorcycles to air conditioners and sirens has increased almost geometrically. It' s no wonder that in many areas of the country, especially in the suburbs, the average sound level has doubled in 20 years. Noise experts estimate that city noises are increasing a half-decibel a year. They found that in 1971 the quietest parts of Los Angeles--thought to be a relatively quiet city--were louder than the loudest districts of New York in 1937.
This passage mainly talks about ______ .
A．the problem of the supersonic transport plane, the Concorde
B．a comparison between the Concorde and other machines
C．the problem of noise
D．noise in the suburbs
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