单选题It is understandable that early civilizations blamed storms on the gods.

单选题The word “smog” first appeared in 1952.

单选题We learn from this passage that

单选题Seeing Red Means Danger Ahead The color red often means danger and by paying attention, (51) can be prevented. At railroad crossings, flashing red fights warn cars to stay back. A red light at a traffic intersection tells cars to stop, so (52) don't run into other cars. In the future, the color red also may help prevent danger (53) construction sites. Thanks to new work by engineers, bridge supports or other kinds of materials could one day contain a color-changing material. It will turn red (54) a structure collapses or falls (55) . A tiny molecule may make a big difference in future warning systems. A polymer (56) a color-changing molecule called a mechanophore turns red seconds before it snaps. The technology may one day allow damage to materials or structures to be easily (57) . The secret behind the color-changing material is a particular type of molecule. A molecule is a group of atoms held together by (58) bonds. Molecules come in all shapes and sizes, and make up (59) you can see, touch or feel. How a molecule behaves depends on what kinds of atoms it contains, and how they're held together. When a polymer containing a color-changing molecule called a mechanophore is about to breaks, it produces a color. When a polymer with mechanophore molecules becomes "injured" or (60) , one of the mechanophore bonds breaks and the material turns red. "It's a really simple detection method," says Nancy Sottos, one of the scientists who worked on the project. "We're (61) up this one bond, and it changes color." Sottos and her team tested the color-changing polymers in their lab. The test (62) proved encouraging. There is a way to get rid of the red color: (63) . When a bright light is shone on the mechanophore, the broken bond is fixed on and the red color disappears. This "self-healing" may be a problem for engineers. They need to use the color-changer in big construction projects that will be (64) , in sunlight. And sunlight will make the mechanophore's warning system useless. Sottos and her fellow scientists still have (65) work to do before the color-changing molecules can be used outside the lab.

单选题Their parents once 1iVed under very {{U}}severe {{/U}}conditions．

单选题On the brink of matrimony, he fled to a desert island.

单选题The new theory was corroborated. A. confirmed B. bleached C. hurled D. refrained

单选题From the incident, they have learned that prompt decisions often lead to biaer regrets.A. urgenB. hastyC. immediateD. wise

单选题Internet Technology Influence on Information Industry Wild Bill Donovan would have loved the Internet. The American spymaster who built the Office of Strategic Services in the World War Ⅱ and later laid the roots for the CIA was fascinated with information. Donovan believed in using whatever tools came to hand in the "great game" of espionage—spying as a "profession". These days the Net, which has already remade such everyday pastimes as buying books and sending mail, is reshaping Donovan"s vocation as well. The latest revolution isn"t simply a matter of gentlemen reading other gentlemen"s e-mail. That kind of electronic spying has been going on for decades. In the past three or four years, the World Wide Web has given birth to a whole industry of point-and-click spying. The spooks call it "open-source intelligence", and as the Net grows, it is becoming increasingly influential. In 1995 the CIA held a contest to see who could compile the most data about Burundi. The winner, by a large margin, was a tiny Virginia company called Open Source Solutions, whose clear advantage was its mastery of the electronic world. Among the firms making the biggest splash in this new world is Straitford, Inc., a private intelligence-analysis firm based in Austin, Texas. Straitford makes money by selling the results of spying (covering nations from Chile to Russia) to corporations like energy-services firm McDermott International. Many of its predictions are available online at www.straitford.com. Straitford president George Friedman says he sees the online world as a kind of mutually reinforcing tool for both information collection and distribution, a spymaster"s dream. Last week his firm was busy vacuuming up data bits from the far corners of the world and predicting a crisis in Ukraine. "As soon as that report runs, we"ll suddenly get 500 new Internet signups from Ukraine," says Friedman, a former political science professor. "And we"ll hear back from some of them." Open-source spying does have its risks, of course, since it can be difficult to tell good information from bad. That"s where Straitford earns its keep. Friedman relies on a lean staff of 20 in Austin. Several of his staff members have military-intelligence backgrounds. He sees the firm"s outsider status as the key to its success. Straitford"s briefs don"t sound like the usual Washington back-and-forthing, whereby agencies avoid dramatic declarations on the chance they might be wrong. Straitford, says Friedman, takes pride in its independent voice.

单选题A peculiarly pointed chin is his most memorable facial characteristic .

单选题{{U}}Persistent{{/U}} attempts to interview Garbo were fruitless.

单选题The great changes of the city astonished every visitor to that city.

单选题{{B}}第三篇{{/B}} {{B}}Geography and Movement{{/B}} To understand how astrology works, we should first take a quick look at the sky. Although the stars are at enormous distances, they do indeed give the impression of being affixed to the inner surface of a great hollow sphere surrounding the earth. Ancient people, in fact, literally believed in the existence of such a celestial sphere. As the earth spins on its axis, the celestial sphere appears to turn about us each day, pivoting at points on a line with the earth’s axis of rotation. This daily turning of the sphere carries the stars around the sky, causing most of them to rise and set, but they, and constellations they define, maintains fixed patterns on the sphere, just as the continent of Australian maintains its shape on a spinning globe of the earth. Thus the stars were called fixed stars. The motion of the sun along the ecliptic is, of course, merely a reflection of the revolution of the earth around the sun, but the ancients believed the earth was fixed and the sun had and independent motion of its own, eastward among the stars. The glare of sunlight hides the stars in daytime, but the ancients were aware that the stars were up there even at night, and the slow eastward motion of the sun around the sky, at the rate of about thirty degrees each month, caused different stars to be visible at night at different times of the year. The moon, revolving around the earth each month, also has an independent motion in the sky. The moon, however, changes it position relatively rapidly. Although it appears to rise and set each day, as does nearly everything else in the sky, we can see the moon changing position during as short an interval as an hour or so. The moon’s path around the earth lies nearly in the same plane as the earth’s path around the sun, so the moon is never seen very far from the ecliptic in the sky. There are five other objects visible to the naked eye that also appear to move in respect to the fixed background of stars on the celestial sphere. These are the planets Mercury, Venus, Mars, Jupiter, and the Saturn. All of them revolve around the sun in nearly the same plane as the earth does, so they, like the moon, always appear near the ecliptic. Because we see the planets from the moving earth, however, they behave in a complicated way, with their apparent motions on the celestial sphere reflecting both their own independent motions around the sun and our motion as well.

单选题The room was Ufurnished/U with the simplest essentials, a bed, a.chair, and a table.

单选题The river widens considerably as it begins to turn east.

单选题The Robot Man According to Hans Moravec, universal robots will take over all the physical activities that we engage in, leaving us with little to do. Moravec sees four generations on the road to true universal robots. The first generation will be here by 2010 and will consist of free-ranging robots that can navigate by building an internal mental map of their surroundings. In new situations they"ll be able to adapt, unlike today"s mobile industrial robots. These robots will have the computing power to cope with simple speech and text recognition, and will be used for tasks such as domestic cleaning. The second generation will arrive around 2020 and will be distinguished by the ability to learn. Second generation robots are programmed with sets of primitive tasks and with feedback that provide "pleasure" and "pain" stimuli. For example, a collision provokes a negative response, a completed task would be positive. Move forward another ten years to 2030 and you get to generation three. This robot can build internal simulations of the world around it. Before beginning a task, it can imagine what will happen in order to predict problems. If it has a free moment, it can replay past experiences and try variations in order to find a better way of doing things next time. It could even observe a person or another robot performing a task and learn by imitation. For the first time, we have here a robot that can think. By the time we get to generation four in 2040, Moravec predicts that robots will be able to: match human reasoning and behaviour; generalise abstract ideas from specific experience; and, conversely, compile detailed plans of action from general commands such as "earn a living" or "make more robots". The Moravec manifesto(宣告) runs something like this. As robots start to become useful in generation one, they"ll begin to take on many tasks in industry. Driven by the availability of this cheap and tireless labour force, the economy will boom and the demand for robots will grow so rapidly that they will soon become low-cost commodity items. So much so that they"ll move into the home, where the domestic robot will relieve us of many chores. With increasing automation in generations two and three, the length of the average working day will plummet , eventually to near zero. Most people will be unemployed as robots take over not just primary industry, but the service economy too. Moravec sees the fourth generation as an opportunity to surpass our human limitations. These future machines will be our "mind children". Like biological children of previous generations, they will embody humanity"s best hope for a long-term future.

单选题The development of the transistor and integrated circuits revolutionized the electronics industry by allowing components to be packaged more densely.A. compactlyB. inexpensivelyC. quicklyD. carefully

单选题The student is collecting material for his science report.

单选题Inflation Business and government leaders also consider the inflation rate to be an important general indicator. Inflation is a period of increased spending that causes rapid rises in prices. (51) your money buys fewer goods so that you get (52) for the same amount of money as before, inflation is the problem. There is a general rise (53) the price of goods and services. Your money buys less. Sometimes people describe inflation as a time when "a dollar is not worth a dollar anymore". Inflation is a problem for all consumers. People who live on a fixed income are hurt the (54) . Retired people, for instance, cannot count on an increase in income as prices rise. Elderly people who do not work face serious problems in stretching their incomes to (55) their needs in time of inflation. Retirement income (56) any fixed income usually does not rise as fast as prices. Many retired people must cut their spending to (57) rising prices. In many cases they must stop (58) some necessary items, such as food and clothing. Even (59) working people whose incomes are going up, inflation can be a problem. The (60) of living goes up, too. People who work must have even more money to keep up their standard of living. Just buying the things they need costs more. When incomes do not keep (61) with rising prices, the standard of living goes down. People may be earning the same amount of money, but they are not living as well because they are not able to buy as many goods and services. Government units gather information about prices in our economy and publish it as price indexes (62) the rate of change can be determined. A price index measures changes in prices using the price for a (63) year as the base. The base price is set at 100, and the other prices are reported as a (64) of the base price. A price index makes (65) possible to compare current prices of typical consumer goods, for example, with prices of the same goods in previous years.

单选题Some psychologists argue that the traditional idea" spare the rod and spoil the child" is not reasonable.A. helpfulB. kindC. sensibleD. effective