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A．undetermined
B．insignificant
C．unusual
D．indisputable
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更多“Some physicists have proposed that sunspots and solar wind have negligible effects on the”相关的问题
第1题
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.
第2题
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.
第3题
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.
第4题
A.mockery… distinct
B.armature… laughable
C.specter … congruous
D.skeleton… recognizable
E.treatment… suspect
第5题
The author suggests in the second paragraph that （）.
A.while some physicists conclude from the laws of nature that there is a God, others draw no such conclusion
B.it is only by studying philosophy that a man can develop religious beliefs
C.by examining a living cell under a microscope biologists can under stand the process of evolution
D.there is a disparity of thinking between scientists and people from other walks of life regarding science and religion
第6题
To get a sense of how women have progressed in science take a quick tour of the physics department at the University ofCalifornia,Berkeley.This is a storied place the 36 of some of the most important discoveries in modern science-starting withErnest Lawrence' s invention of the cvclotron(回旋加速器)in 1931.
A、 generation ago female faces were 37 and,even today,visitors walking through the first floor of LeConte Hall will See a full corridor of exhibits 38 the many distinguished physicists who made history here, 39 all of there white malesBut climb up to the third floor and you' II see a 40 display.There,among the photos of current facnlty members and students are portraits of the 41 head of the department,Marjorie Shapiro and four other women whose reseaich 42 everything from the mecheanics of the universe to the smallest particles of matter.
A、sixth woman was hired just two weeks ago.Although they' re Still only about 10 percent of the physics faculty,women are clearly a presence here.And the real 43 may be in the smaller photos to the right graduate and undergraduate students about 20 percent of them female.Every yearsBerkeley sends its fresh female physics PhDs to the country' S top universities.That makes Shapiro optimistic but also 44 "I believe things are getting bette "she says "but they' re not getting better as 45as i would like."
A.circumstance
B.confidence
C.covers
D.current
E.deals
F.different
G.exposing
H.fastl
第7题
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.
第8题
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请帮忙给出每个问题的正确答案和分析，谢谢！
第9题
Psychologists have noticed that larger units of time. such as months and years, fly on swifter wings as we age.
They also note that the more time is structured with schedule and appointments, the more rapidly it seems to pass. For example, a day at the beach. Since most of us spend fewer days at the beach and more at the office, an increase in structured time could well be to blame why time seems to speed up as we grow older.
Expectation and familiarity also make time seem to flow more rapidly. Almost all of us have had the experience of driving somewhere we've never been before. Surrounded by unfamiliar scenery, with no real notion of when we'll arrive, we experience the trip as lasting a long time. But the return trip, although exactly as long, seems to take far less time. The novelty of the outward journey has become routine. Thus taking a different route on occasions can often help slow the clock.
When days become as identical as beads(珠子) on a string, they blend together, and even months become a single day. To counter this, try to find ways to interrupt the structure of your day--to stop time, so to speak.
Learning something new is another way to slow the passage of time. One of the reasons the days of our youth seem so full and long is that these are the days of learning and discovery.
The purpose of this passage is to ______.
A．show the different ideas of physicists and psychologists on time
B．state the principles of time
C．describe various notions about time
D．explain why time flies and how to slow it down
第10题
Albert Einstein was the first to suggest the existence of stimulated emission in a paper published in 1917. However, for many years physicists thought that atoms and molecules always were much more likely to emit light spontaneously and that stimulated emission thus al- ways would be much weaker. It was not until after the Second World War that physicists began trying to make stimulated emission dominate. They sought ways by which one atom or molecule could stimulate many others to emit light, amplifying it to much higher powers.
The first to succeed was Charles H. Townes, then at Columbia University in New York. Instead of working with light, however, he worked with microwaves, which have a much longer wavelength, and built a device he called a "maser" for Microwave Amplification by the Stimulated Emission of Radiation. Although he thought of the key idea in 1951, the first maser was not completed until a couple of years. Before long, many other physicists were building masers and trying to discover how to produce stimulated emission at even shorter wavelengths.
The key concepts emerged about 1957. Townes and Artyur Schawlow, then at Bell Telephone Laboratories, wrote a long paper outlining the conditions needed to amplify stimulated emission of visible light waves. At about the same time, similar ideas crystallized in the mind of Gordon Gould, then a 37-year-old graduate student at Columbia, who wrote them down in a series of notebooks. Townes and Schawlow published their ideas in a scientific journal, Physical Review Letter, but Gould filed a patent application. Three decades later, people still argue about who deserves the credit For the concept of the laser.
The word "it" (line 5, para 1) refers to______.
A．light bulb
B．energy
C．molecule
D．atom
