同济考博英语真题2007

C. Fire is a portable, inanimate source of energy.

D. Man sometimes makes use of energy available in the bodies of stronger species. 22. From the passage we know ___.

A. fire made human beings free from bacterial and parasitic infestation

B. fire enabled human beings to deal with immediate emergencies more efficiently C. fire made some animals frightened

D. fire helped human beings change their eating habits completely

23. Judging from the context, the phrase \

means____.

A. adventurous B. unhappy C. wandering D. unstable 24. The point of similarity between a complex, human society and a complex bee society is ___.

A. the division of labor B. the use of fire

C. the development of industry D. the development of a written language 25 .According to the passage, insect societies ___. A. are governed by the instincts of insects

B. are not fundamentally different from human societies C. are composed of individuals of the same type D. are as not warlike as human beings

Passage Two

Modem technology may not have improved the world all that much, but it certainly has made life noisier. Unmuffled motorcycles, blaring car alarms, and roving boom boxes come first, second, and third on my list of most obnoxious noise offenders, but everyone could come up with his own version of aural hell—if he could just find a quiet spot to ponder the matter. Yet what technology has done, other technology is now starting to undo, using computer power, to zap those ear-splitting noises into silence. Previously silence-seekers had little

recourse except to stay inside, close the windows, and plug their ears. Remedies like these are quaintly termed \ passive\sound. Now computer technology is producing a far more effective \doesn't just contain, deflect, or mask the noise but annihilates it electronically.

The system works by countering the offending noise with -\anti-noise\sinister-sounding term that calls to mind antimatter, black holes, and other Popular Science mindbenders but, that actually refers to something quite simple. Just as a wave on a pond is flattened when it merges with a trough that is its exact opposite (or mirror image), so can a sound wave be negated by meeting its opposite.

This general theory of sound cancellation has been around since the 1930s. In the fifties and sixties it made for a kind of magic trick among laboratory acousticians 5

playing around with the first clunky mainframe computers. The advent of low-cost, high-power microprocessors has made active noise-cancellation systems a commercial possibility, and a handful of small electronics firms in the United States and abroad are bringing the first ones onto the silence market.

Silence buffs might be hoping that the noise-canceling apparatus will take the shape of the 44 Magnum wielded by Dirty Harry, but in fact active sound control is not quite that active. The system might more properly be described as reactive, in that it responds to sound waves

already headed toward human ears. In the configuration that is usual for such systems

microphones detect the noise signal and send it to the system's microprocessor, which almost instantly models it and creates its inverse for loudspeakers to fire at the original. Because the two sounds occupy the same range of frequencies and tones, the inverse sounds exactly like the noise it is meant to eliminate: the anti-noise canceling Beethoven's Fifth Symphony is heard as Beethoven's Fifth. The only difference is that every positive pressure produced on the air by the orchestra is matched by a negative pressure produced by the computer, and every negative pressure is matched by a positive, thereby silencing the sound. The system is most effective as a kind of muffler, in which microphones, microprocessor, and loudspeaker are all in a unit encasing the device that produces the sound, stifling it at its source. But it can work as a headset, too, negating the sound at the last moment before it disturbs one's peace of mind. 26.The writer holds that ___.

A. modem technology has disturbed the quiet life of the people B. modem

technology has made people indifferent to noise pollution C. modem technology has made the present world quieter than before D. modem technology has failed to solve the problem of noise pollution

27. According to the passage, an active noise-cancellation system ___. A. contains noise

rather than negates it B. eliminates noise rather than muffles it C. deflects noise rather than baffles it D. holds noise back rather than stifles it 28. In Paragraph 5 the word \ buffs\ B. enthusiasts C. buyers D. manufacturers 29. Which of the following statements is Not true according to the passage? A. In the past, people sometimes plugged their ears to fight against the offending

noise. B. An active noise-cancellation system follows the principle of a wave being flattened by meeting its exact opposite. C. The first active noise-cancellation system was made in the 1930s, D. Active noise-cancellation systems are no w- available on the market.

30. Active noise-cancellation systems require ___. A. microphones B. microprocessors C. loudspeakers D. all of the above

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Passage Three

In the early years of the twentieth century, astrophysicists turned their attention to a special category of stars, known as cepheid (辐射点在仙王(星)座中的流星) variables. A variable star is one whose apparent brightness changes from time to time. Among some variables, the change in brightness occurs so slowly as to be almost imperceptible; among others, it occurs in sudden, brief, violent bursts of energy. Cepheid variables have special characteristics that make them a useful astronomical tool.

It was Henrietta Leavitt, an astronomer at the Harvard Observatory, who first examined the cepheid variables in detail. She found that these stars vary regularly in apparent brightness over a relatively short period of time - from one to three days to a month or more. This

variation in brightness could be recorded and precisely measured with the help of the camera, then still a new tool in astronomy.

Leavitt also noticed that the periodicity of each cepheid variable - that is, the period of time it took for the star to vary from its brightest point to its dimmest, and back to its brightest

again—corresponded to the intrinsic or absolute brightness of the star. That is, the greater the star's absolute brightness, the slower its cycle of variation.

Why is this so? The variation in brightness is caused by the interaction between the star's gravity and the outward pressure exerted by the flow of light energy from the star. Gravity pulls the outer portions of the star inward, while light pressure pushes them outward. The result is a pulsating, in-and-out movement that produces increasing and decreasing brightness. The stronger the light pressure, the slower this pulsation. Therefore, the periodicity of the cepheid variable is a good indication of its absolute brightness.

Furthermore, it is obvious that the more apparent brightness of any source of light decrease the further we are from the light. Physicists had long known that this relationship could be described by a simple mathematical formula. If we know the absolute brightness of any object - say, a star - as well as our distance from that object, it is possible to use the inverse square law to determine exactly how bright that object will appear to be.

This laid the background for Leavitt's most crucial insight. As she had discovered, the absolute brightness of a cepheid variable could be determined by measuring its periodicity. And, of course, the apparent brightness of the star when observed from the earth could be determined by simple measurement. Leavitt saw that with these two facts and the help of the inverse square law, it would be possible to determine the distance from earth of any cepheid variable. If we know the absolute brightness of the star and how bright it appears from the earth, we can tell how far it must be.

Thus, if a cepheid variable can be found in any galaxy, it is possible to measure the distance of that galaxy from earth. Thanks to Leavitt's discovery, astronomical distances that could not previously be measured became measurable for the first time. 31 .The primary purpose of the passage is to explain

A. the background and career of the astronomer Henrietta Leavitt B. how and why various categories of stars vary in brightness

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C. important uses of the camera as an astronomical tool

D. how a particular method of measuring astronomical distances was created 32. According to the passage, the absolute brightness of a cepheid variable ____. A. depends upon its measurable distance from an observer on earth B. may be determined from the length of its cycle of variation

C. changes from time to time according to a regular and predictable pattern D. indicates the strength of the gravitation force exerted by the star

33. Which of the following did Leavitt's work provide astronomers with the means of determining?

A. The absolute brightness of any observable cepheid variable.

B. The apparent brightness of any object at a given distance from an observer. C. The distance from earth of any galaxy containing an observable cepheid variable. D. Both A and C.

34. Cepheid variable of great absolute brightness would probably exhibit ____.

A. a relatively rapid variation in brightness B. a correspondingly weak gravitational force C. slow and almost invisible changes in brightness D. a strong outward flow of light pressure

35. The passage implies that Leavitt's work on cepheid variables would not have been

possible without the availability of____. A. the camera as a scientific tool

B. techniques for determining the distances between stars C. a method of measuring a star's gravitational force D. an understanding of the chemical properties of stars

Passage four

The American economy, whether in government or private industry, has found retirement a convenient practice for managing the labor force. On the positive side, widespread retirement has meant an expansion of leisure and opportunities for self-fulfillment in later life. On the negative side, the practice of retirement entails large costs, both in funding required for pension systems and in the loss of the accumulated skills and talents of older people. Critics of retirement as it exists today have pointed to the rigidity of retirement practices: for example, the fact that retirement is typically an all-or-nothing proposition. Would it not be better to have some form of flexible or phased retirement, in which employees gradually reduce their work hours or take longer vacations? Such an approach might enable older workers to adjust better to retirement, while permitting employers to make gradual changes instead of coping with the abrupt departure of an employee. Retirement could be radically redefined in the future.

Earlier criticism of mandatory retirement at a fixed age led to legal abolition of the practice, for the most part, in 1986, The same kind of criticism has been leveled at the practice of age discrimination in employment. The Age Discrimination in Employment Act forbids older workers from being limited or treated in any way that would harm their employment possibilities. Still, most observers admit that age 8

discrimination in the workplace remains widespread. The negative stereotypes of older

workers have caused employers to be reluctant to hire or train older people. Sometimes such discrimination against older workers is based on mistaken ideas, such as the false belief that older workers are less productive. In fact, empirical studies have not shown older workers to be less dependable in their job performance, nor are their absenteeism rate higher.

Interest in the potential productivity of older workers has stimulated the growth of industrial gerontology, a field concerned with recruitment, performance appraisal, retraining, and

redesign of jobs to permit older workers to be more productive. Managing an older workforce will clearly be a challenge for the future. There is also much support for the idea of work life extension; that is, adaptations of retirement rules or employment practices to enable older people to become more productive. In favor of this idea is the fact that three-quarters of

employed people over 65 are in white-collar occupations in service industries, which are less physically demanding than agriculture or manufacturing jobs. As a result, it is sometimes argued, older people can remain in productive jobs now longer than in the past. In addition, some analysts point to declining numbers of young people entering the workforce, thus anticipating a labor shortage later in the 1990s. That development, if it occurred, might