It demonstrates why it is essential that we focus efforts on measures to help prevent olderApeople from becoming ill in the first place and on having excellent health and social careB Cservices for them since they do. D
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With many ethnic groups represented, the student union is very （ ）.
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The extremely （ ）trade in endangered species is proving irresistible to countries in grave currency crisis.
A.lucrative B.approximate C.ambitious D.prospective -
t="" produce="" a="" movie="" simulating="" fight="" on="" the="" screen="" in="" real="" time”，="" says="" weidhaas.="" there="" is="" way="" around="" problem:="" two="" movies="" have="" been="" made="" using="" still="" pictures="" generated="" by="" computer="" as="" individual="" frames.="" “the="" results="" were="" impressive,”="" lie="" says,="" “bat="" it="" was:="" cumbersome="" to="" do.="" at="" twenty-four="" frames="" per="" second,="" takes="" fourteen="" hundred="" separate="" images,="" make="" one-minute="" film.”="" another="" limitations:="" can="" access="" only="" enough="" memory="" cover="" 15-mile="" square="" area.="" an="" “observer”="" high="" up="" will="" see="" blank="" spaces="" beyond="" those="" limits.Weidhaas wants to add information about what overlies the terrain-cities, vegetation, roads; and so on. “Making the image as realistic as possibly will make our advice more effective he says, “and might lead to uses we haven't thought of yet.”1.As used in the first paragraph, terrain most clearly means （ ）.2.Livermore’s computer map, in combination with weather report, might be useful in predicting （ ）.3.The information used by the computer to make its detailed maps （ ）.I. was gathered by the Defense Department and the U.S. Geological SurveyII. shows points roughly 200 feet apart.III. involves altitude measurements.4.Which of the following is the best description of ray tracing?5.Information about cities, vegetation, and road overlying the terrain（ ）.'>
Imagine an accident in which a nuclear power plant releases radioactive gas. The cloud starts moving with the wind. Clearly the authorities will want to evacuate anyone in its path, but what is that path? Local wind information is meaningless without information about terrain; a mountain range or series of valleys can divert both wind and gas in unpredictable directions.To make “downwind” a useful term, scientists at Lawrence Livermore National Laboratory have put United States on a computer, the entire United States — every hill, every valley, every mile of seashore. Within minutes of a disaster, they can give meteorologists a context for weather data, and thus the ability to predict how toxic gases might spread.The database for this computer map is a series of altitude measurements, made over many years by the Defense Department and the U.S. Geological Survey. They represent the height above sea level of over a billion separate points — a grid of points 200 feet apart, spanning the country. Armed with these data, plus a program that manipulates them, a Cray-1 computer can produce an image of any piece of terrain, seen from any angle, illuminated by an imaginary sun atany time of day placing the “observer” at any altitude from zero to 40,000 feet.“We use a technique called ray tracing” says Patrick Weidhass, one of the Livermore computer scientists who wrote the program. The computer is told where the observer is. The program traces an imaginary ray from there outward until it “ intersects" with one of the points of altitude reworded in the machines memory. The computer them puts a lot of color at the proper place on the screen, and the program traces another ray.At its highest resolution of 2,000 horizontal and 1,700 vertical dots per picture, the computer has to trace several million rays. Even on the Cray, the most powerful computer in the world, this takes about a minute. Reducing the resolution to 400- 300 (a TV screen has 800 x 700)speeds it up to about eight seconds. "We can't produce a movie simulating fight on the screen in real time”， says Weidhaas. There is a way around the problem: Two movies have been made using still pictures generated by the computer as individual frames. “The results were impressive,” lie says, “bat it was: cumbersome to do. At twenty-four frames per second, it takes fourteen hundred separate computer images, to make a one-minute film.” Another limitations: The computer can access only enough memory to cover a 15-mile square area. An “observer” high up will see blank spaces beyond those limi
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sleep="" alternation="" with="" some="" 16-17="" hours'="" wakefulness="" and="" that,="" broadly="" speaking,="" the="" normally="" coincides="" hours="" of="" darkness.="" our="" present="" concern="" is="" how="" easily="" to="" what="" extent="" this="" cycle="" can="" be="" modified. The question is no mere academic one. The ease, for example, with which people can change from working in the day to working at night, is a question of growing importance in industry where automation calls for round-the-clock working of machines. It normally takes from five days to one week for a person to adapt to reversed routine of sleep and wakefulness, sleeping during the day and working at night. Unfortunately, it is often the case in industry that shifts are changed every week; a person may work from 12 midnight to 8 a m one week, 8 a m to 4 p. m the next, and 4 p. in to 12 midnight the third and so on. This means that no sooner has he got used to one routine than he has to change to another, so that much of his time is spent neither working nor sleeping very efficiently. The only real solution appears to be to hand over the night shift to a number of permanent night workers. An interesting study of the domestic life and health of night-shift workers was carried out by Brown in 1957. She found a high incidence（发生率）of disturbed sleep and other disorders among those on alternating day and night shifts, but no abnormal occurrence of these phenomena among those on permanent night work. This latter system then appears to be the best long-term policy, but meanwhile something may be done to relieve the strains of alternate day and night work by selecting those people who can adapt most quickly to the changes of routine. One way of knowing when a person has adapted is by measuring his body temperature. People engaged in normal daytime work will have a high temperature during the hours of wakefulness and a low one at night; when they change to night work the pattern will only gradually go back to match the new routine and the speed with which it does so parallels, broadly speaking, the adaptation of the body as a whole, particularly in terms of performance. Therefore, by taking body temperature at intervals of two hours throughout the period of wakefulness it can be seen how quickly a person can adapt to a reversed routine, and this could be used as a basis for selection. So far, however, such a form of selection does not seem to have been applied in practice. 1.Why is the question of “how easily people can get used to working at night” not a mere academic question? 2.The main problem of the round-the-clock working system lies in （ ）. 3.The best solution for implementing the 24-hour working system seems to be （ ）. 4.It is possible to find out if a person has adapted to the changes of routine by measuring his body temperature because （ ）. 5.Which of the following statements is NOT TRUE?'>
We all know that the normal human daily cycle of activity is of some 7-8 hours' sleep alternation with some 16-17 hours' wakefulness and that, broadly speaking, the sleep normally coincides with the hours of darkness. Our present concern is with how easily and to what extent this cycle can be modified.The question is no mere academic one. The ease, for example, with which people can change from working in the day to working at night, is a question of growing importance in industry where automation calls for round-the-clock working of machines. It normally takes from five days to one week for a person to adapt to reversed routine of sleep and wakefulness, sleeping during the day and working at night. Unfortunately, it is often the case in industry that shifts are changed every week; a person may work from 12 midnight to 8 a m one week, 8 a m to 4 p. m the next, and 4 p. in to 12 midnight the third and so on. This means that no sooner has he got used to one routine than he has to change to another, so that much of his time is spent neither working nor sleeping very effic
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At present rates of demand, the world has enough oil in known and economically viable reserves to last for more than 40 years, enough gas for more than 60 years and enough coal for more than 230 years. Naturally, demand will increase; but so will reserves as companies explore more widely and costs fall. Since 1970 viable reserves of oil have almost doubled while those of gas have leapt three-fold. One distant day a difficult situation will come, but as it approaches, fossil-fuel prices will rise, making alternative forms of energy, perhaps including nuclear power, competitive. That is no reason to spend on nuclear right now.All oil shock is a more worrying prospect despite today’s low oil price and OPEC’s present inability to budge it upwards. However, even if an oil shock is a real danger, building nuclear reactors is not a good way to avert it. A higher oil price would have a relatively small effect on the supply of electricity-the only sort of energy that nuclear power can now provide. Just over a tenth of the world’s electricity is generated from oil, and the proportion has steadily fallen since 1970. Transport, by contrast, relies almost entirely upon oil, already swallowing half the world’s oil supply and likely to take an even larger chunk in the future. If the supply of oil were cut off tomorrow, billions of people would find themselves immobile. Relatively few would be without electricity.The congestion and pollution are serious problems, and they could try to restrict the growth of car use, or promote cars which use less fuel. For governments keen to reduce electricity’s dependence on oil still further, there are usually cheaper alternatives to nuclear, such as coal or hydro power.Climate change is a legitimate worry. Although still riddled with uncertainties, the science of climate change is becoming firmer: put too much carbon in the atmosphere and you might end up cooking the earth, with possible catastrophic results. But here again switching immediately to nuclear power is not the best response. Cutting the larger subsidies that go to the world’s coal producers would help tilt the world’s energy balance towards natural gas, which gives off much less carbon dioxide. Developing countries subsidize electricity prices up to $120 billion a year, according to World Bank estimates. If price reflected the true costs of generation, electricity demand would fall, thus, cutting greenhouse emissions.1.What is the main idea of the first paragraph?2.Which of the following would NOT be true if an oil shock came soon?3.What is NOT mentioned as a way to prepare for an oil shock?4.What is meant by “cooking the earth”？5.What is the main aim of the passage?
A.Oil, gas and coal play an important role in energy supply. B.The more reserves, the greater demand there is for energy. C.There is no point in bothering about nuclear power at present. D.Some other forms of energy will replace fossil fuels someday.
问题2：
A.It wouldn’t affect much of the supply of electricity. B.It would have great impact on transport. C.The world would be badly in need of nuclear plants. D.Oil price would go upwards.
问题3：
A.Exploiting nuclear energy instead. B.Promoting cars which consume less fuel. C.Building up stock of oil for future consumption. D.Using coal or hydro power.
问题4：
A.The earth is getting wanner as if fueled by carbon dioxide dischargers. B.Owing to the change of climate, there will be less oil reserves C.The power plant emits too much smoke and fume. D.Automobile exhausts give off too much carbon dioxide.
问题5：
A.To reject the idea of turning to nuclear reactors for energy. B.To demonstrate that there are alternative forms of energy. C.To defend oil consumption from the blame for greenhouse effect. D.To warn people of the inevitable exhaustion of fossil fuels.