单选题Pain, unfortunately, is a horrible necessity of life. It protects people by alerting them to things that might injure them. But some long-term pain has nothing to do with any obvious injury. One estimate suggests that one in six adults suffer from a "chronic pain" condition. Steve McMahon, a pain researcher at King's College, London, says that if skin is damaged, for instance with a hot iron, an area of sensitivity develops around the outside of the burn where although untouched and undamaged by the iron the behavior of the nerve fibers is disrupted. As a result, heightened sensitivity and abnormal pain sensations occur in the surrounding skin. Chronic pain, he says, may similarly be caused not by damage to the body, but because weak pain signals become amplified. This would also help explain why chronic pains such as lower-back pain and osteoarthritis fail to respond well to traditional pain therapies. But now an entirely new kind of drug, called Tanezumab, has been developed. It is an antibody for a protein called nerve growth factor (NGF), which is vital for new nerve growth during development. NGF, it turns out, is also crucial in the regulation of the sensitisation of pain in chronic conditions. Kenneth Verburg, one of the researchers involved in the development of Tanezumab at Pfizer, says it is not exactly clear what role NGF plays in normal physiology, but after an injury which involves tissue damage and inflammation, levels of NGF increase dramatically. NGF seems to be involved in transmitting the pain signal. As a consequence, blocking NGF reduces chronic pain. Tanezumab must still complete the final stages of clinical trials before it can become a weapon in the toolkit for reducing human suffering. But unexpected pains do not always come from the body. According to Irene Tracey, a pain researcher at the University of Oxford, how pain is experienced also depends upon a person's state of mind. If successive patients suffer the same burn, the extent to which it hurts will depend on whether one is anxious, depressed, happy or distracted. Such ideas are being explored with brain scans which suggest that even if a low level of pain is being sent to the brain, the signal can be turned up by the "mind" itself. Indeed, patients can even be tricked into feeling pain. In one experiment volunteers were given a powerful analgesic and subjected to a painful stimulus—which, because of the analgesic, they could not feel. Then they were told the drug had worn off (although it had not), and subsequently complained that the stimulus hurt. People can, therefore, feel pain simply because it is expected. They can fail to feel pain for exactly the same reasons, for example when they are given placebos or are distracted. But although pain may be subjective, that does not mean the final experience is controlled solely by the mind. A recent paper in Proceedings of the National Academy of Sciences has shown that genes play a role in determining sensitivity to pain. One gene, known as SCN9A, codes for a protein that allows the channels along which nerve signals are transmitted to remain active for longer and thus transmit more pain signals. It seems likely that this protein will attract a great deal more analgesic research. Variations in SCN9A may also explain why some patients prefer different classes of painkillers. Although pain may be a horrible necessity, there is no doubt that humanity could cope with far less of the chronic sort. Understanding how the mind, the body and people's genes interact to cause pain should bring more relief.

单选题{{B}}Text 3{{/B}} Climatic conditions are delicately adjusted to the composition of the Earth's atmosphere. If there were a change in the atmosphere--for example, in the relative proportions of atmospheric gases"-the climate would probably change also. A slight increase in water vapor, for instance, would increase the heat-retaining capacity of the atmosphere and would lead to a rise in global temperatures. In contrast, a large increase in water vapor would increase the thickness and extent of the cloud layer, reducing the amount of solar energy reaching the Earth's surface. The level of carbon dioxide in the atmosphere has an important effect on climatic change. Most of the Earth's incoming energy is short-wavelength radiation, which tends to pass through atmospheric carbon dioxide easily. The Earth, however, reradiates much of the received energy as long-wavelength radiation, which carbon dioxide absorbs and then remits toward the Earth. This phenomenon, known as the greenhouse effect, can result in an increase in the surface temperature of a planet. An extreme example of the effect is shown by Venus, a planet covered by heavy clouds composed mostly of carbon dioxide, whose surface temperatures have been measured at 43012. If the carbon dioxide content of the atmosphere is reduced, the temperature falls. According to one respectable theory, if the atmospheric carbon dioxide concentration were halved, the Earth would become completely covered with ice. Another equally respectable theory, however, states that a halving of the carbon dioxide concentration would lead only to reduction in global temperatures of 312. If, because of an increase in forest fires or volcanic activity, the carbon dioxide content of the atmosphere increased, a warmer climate would be produced. Plant growth, which relies on both the warmth and the availability of carbon dioxide, would probably increase. As a consequence, plants would use more and more carbon dioxide. Eventually carbon dioxide levels would diminish and the climate, in turn, would become cooler. With reduced temperatures many plants would die; carbon dioxide would thereby be returned to the atmosphere and gradually the temperature would rise again. Thus, if this process occurred, there might be a long-term oscillation in the amount of carbon dioxide present in the atmosphere, with regular temperature increases and decreases of a set magnitude. Some climatologists argue that the burning of fossil fuels has raised the level of carbon dioxide in the atmosphere and has caused a global temperature increase of at least 1 C. But a supposed global temperature rise of 112 may in reality be only several regional temperature increases, restricted to areas where there are many meteorological stations and mused simply by shifts in the pattern of atmospheric circulation. Other areas, for example, the Southern Hemisphere Oceanic Zone, may be experiencing an equivalent temperature decrease that is unrecognized because of the shortage of meteorological recording stations.

单选题With which of the following opinions would the author be likely to agree?______

单选题The working conditions of skilled workers in the meat-packing industry during the 1880’s were influenced by

单选题All the following are mentioned in the passage as reasons why children should learn science EXCEPT______.

单选题What is less well understood by the general public is that- there have been a number of trends which have further contributed to the diminishment of excavation as an activity. As Bahn puts it "there have been two major trends over time: first, excavation has become far slower and more painstaking .... The work is incredibly meticulous... Secondly, we can learn far more from what we have." The conclusions to be drawn from this would appear to be contradictory. As technology improves we are able to undertake a wide variety of analysis from microscopic, radio carbon dating or even DNA 'samples. The ability to determine more, from fewer samples again suggests that less excavation is required. Moreover, more often than not the balance of effort now rests with the specialist analysis such as pollen experts and dating analysis rather than the excavators. So, again some of the requirements for extensive excavation have diminished through the advancement of other analytical techniques and not just surface survey techniques. Furthermore, Archaeology itself has changed in a number of ways. No longer is the emphasis simply upon the acquisition of material culture or artefacts. In many cases, we have a reasonable understanding of the surviving material culture, Indeed, in Egypt and Italy, items are rebuffed in the ground simply because the museums are too full, theft may be ripe, preservation difficult and documentation slow. The emergence d processual archaeology under Binford and others again moved archaeology towards broader concepts of explanation, process, deduction, hypothesis testing, question setting and response. Answering questions about the organisation of societies, the environment and their life have a much greater importance today. And answering these how and why questions implies a much broader scope of work. Excavation alone cannot answer all these questions. Archaeology needs a structured research' process. This procedure is described by Renfrew and Bahn as research design. Research design has four components, namely: formulation, the collection and recording, processing and analysis and publication. For example, more detailed work in the formulation part can focus lines of enquiry into a specific area and thereby again reduce the amount of excavation required. As the questions currently posed by Archaeologists tend to be more 'strategic' the focus of the field work is also of a strategic nature. Overall landscapes, context, trading patterns and systems are more important than individual sites. As such this requires different techniques. AS Greene states "field work today is rarely directed at a single site. It usually forms part of a comprehensive study of an area." He continues "studies are designed to elucidate the broad agricultural, economic, and social developments".

单选题Charles Darwin wed his cousin Emma and spawned 10 children, including four brilliant scientists. Albert Einstein’s second wife Elsa was his first cousin. Queen Victoria said “I do” to hers. So have millions worldwide. In parts of Saudi Arabia, 39% of all marriages are between first cousins. In the U. S., though, the practice bears a stigma of inbreeding just this side of incest. The taboo is not only social hut legislative; 24 states ban the marriage of first cousins: five others allow it only if the couple is unable to bear children. A major reason for this ban is the belief that kids of first cousins are tragically susceptible to serious congenital illnesses. That view may have to change. A comprehensive study published recently in the Journal of Genetic Counseling indicates such children run an only slightly higher risk of significant genetic disorders like congenital heart defects — about two percentage points above the average 3% to 4%. Says the study’s lead author, Robin Bennett, president-elect of the National Society of Genetic Counselors, which funded the study: “Aside from a thorough medical family history, there is no need to offer any genetic testing on the basis of consanguinity alone”. Publication of the study will do more than tweak public awareness; it will enlighten doctors who have urged cousin couples not to have children. “Just this week,” says Bennett, “I saw a 23-year-old woman who had had a tubal ligation because her parents were cousins and her doctor told her she shouldn’t have children.” The American proscription against cousin marriages grew in the 19th century as wilderness settlers tried to distinguish themselves from the “savage” Indians, says Martin, author of the book Forbidden Relatives: The American Myth of Cousin Marriage. “The truth is that Europeans were marrying their cousins and Native Americans were not.” And doesn’t God have stern words on the subject? Christie Smith, 37, a Nevada writer, says she felt guilty when she fell in love with her first cousin’s son Mark. “I was trying so hard to convince myself not to have these feelings,” she recalls, “that I went to the Bible looking for confirmation that it was wrong. And what I found was the exact opposite: support for cousin marriages.” The patriarch Jacob married two of his first cousins, Rachel and Leah. Smith married Mark in 1999. The medical ban is lifted; the social stain may take longer to disappear.

单选题Early this week a bit of cheery news was reported by the Manhattan Institute, a conservative think tank: black segregation has hit its lowest point in more than a century — declining in all 85 of the nation's largest metropolitan areas. Nevertheless, the report is largely celebratory in tone, and it has been received in that fashion by much of the news media. Before we break out the champagne, however, it may be wise to pause and reflect for a moment on who was excluded from the analysis. Our nation's prison population has more than quintupled (soaring from 300, 000 in the mid-1970s to more than 2 million today), due to a "get tough" movement and a war on drugs that has been waged almost exclusively in poor communities of color. Studies have consistently shown that people of color are no more likely to use or sell illegal drugs than whites, but a fierce drug war has been waged nonetheless, and harsh mandatory minimum sentences passed, leading to a prison-building boom unprecedented in world history. Despite this sea change, prisoners continue to be treated as nonentities in much sociological and economic analysis. In the Manhattan Institute study, prisoners are not even mentioned, despite the fact that millions of poor people — overwhelmingly people of color — are removed from their communities and held in prisons, often hundreds of miles from home. Most new prison construction has occurred in predominately white, rural communities, and thus a new form of segregation has emerged in recent years. Bars and walls keep hundreds of thousands away from mainstream society — a form of apartheid unlike the world has even seen. If all of them suddenly returned, they would not be evenly throughout the nation's population. Instead they would return to a relatively small number of communities defined by race and class, greatly intensifying the levels of segregation we see today. Those who imagine that the failure to account for prisoners can't possibly affect the analysis would be wise to consider the distortion of unemployment figures in recent years. According to Harvard professor Bruce Western, standard unemployment figures underestimate the true jobless rate by as much as 24 percentage points for less educated black men. In fact, during the 1990s — the economic-boom years — no college black men were the only group that experienced a sharp increase in unemployment, a development directly traceable to the sudden explosion of the prison population. At the same time that unemployment rates were sinking to record low levels for the general population, the true jobless rate among no college black men soared to a staggering 42%. Prisoners do matter when analyzing the severity of racial inequality in the U. S. Yet because they are out of sight and out of mind, it is easy to imagine that we are making far more racial progress than we actually are. For now, let's keep the cork in the bottle and pray that we will eventually awaken from our color-blind slumber to the persistent realities of race in America.

单选题Which of the following is NOT mentioned when the author explains the reasons of the rapid growing number of English speaker?

单选题{{B}}Text 2{{/B}} The question of whether war is inevitable is one, which has concerned many of the world's great writers. Before considering this question, it will be useful to introduce some related concepts. Conflict, defined as opposition among social entities directed against one another, is distinguished from competition, defined as opposition among social entities independently striving for something, which is in inadequate aupply. Competitors may not be aware of one another, while the parties to a conflict are. Conflict and competition are both categories of opposition, which has been defined as a process by which social entities function is the disservice of one another. Opposition is thus contrasted with cooperation, the process by which social entities function in the service of one another. These definitions are necessary because it is important to emphasize that competition between individuals or groups in inevitable in a world of limited resources, but conflict is not. Conflict, nevertheless, is very likely to occur, and is probably an essential and desirable element of human societies. Many authors have argued for the inevitability of war from the premise that in the struggle for existence among animal species, 0nly the fittest survive. In general, however, this struggle in nature is competition, not conflict. Social animals, such as monkeys and cattle, fight to win or maintain leadership of the group. The struggle for existence occurs not in such fights, but in the competition for limited feeding areas and for occupancy of areas free from meat-eating animals. Those who fail in this competition starve to death or become victims to other species. This struggle for existence does not resemble human war, but rather the competition of individuals for jobs, markets, and materials. The essence of the struggle is the competition for the necessities of life that are insufficient to satisfy all. Among nations there is competition in developing resources, trades, skills, and a satisfactory way of life. The successful nations grow and prosper; the unsuccessful decline. While it is true that this competition may induce efforts to expand territory at the expense of others, and thus lead to conflict, it cannot be said that war-like conflict among nations is inevitable, although competition is.

单选题What is the main principle to be observed in following the procedures?______

单选题The main difference between a sport and a game lies in ______.

单选题Few people, except conspiracy theorists, would have expected so public a spat as the one this week between the two ringmasters of Formula One (F1) motor racing. Bernie Ecclestone. a very wealthy British motor sport entrepreneur, is at odds. it would seem. with his longstanding associate. Max Mosley, president of Fl's governing body, the Federation International de l'Automobile (FIA). On the surface, the dispute has broken out over what looked like a done deal. Last June. the FIA voted unanimously to extend Mr. Ecclestone's exclusive fights to stage and broadcast Fl racing, which expire in 2010, by t00 years. For these favourable rights, Mr. Ecelestone was to pay the FIA a mere $360 million in total, and only $60 million immediately. The FIA claims that Mr. Ecclestone has not made the payment of $60 million, a claim denied by Mr. Ecclestone. who insists the money has been placed in an escrow account. Mr. Mosley has asked Mr. Ecclestone to pay up or risk losing the deal for the Fl rights after 2010. perhaps m a group of car makers that own Fl teams. For his part. Mr. Ecclestone has, rather theatrically, accused Mr. Mosley of "trying to do some extortion". What is going on? Only three things can be stated with confidence. First. the idea that Mr. Ecclestone cannot find the 560 million is ridiculous: his family trust is not exactly short of cash. having raised around $2 billion in the past two years. Second. it would not be in Mr. Ecclestone's long-term financial interest to discard a deal which could only enhance the value of his family's remaining 50% stake in SLEC. the holding company for the group of companies that runs the commercial side of F1. Third. the timing of the dispute is very interesting. Why? Because the other.50% stake in SLEC. owned by EM. TV. a debt-ridden German media company, is up for sale. EM. TV badly needs to sell this stake in the near future to keep its bankers at dead end. The uncertainty created by the dispute between Mr. Ecclestone and Mr. Mosley might depress the value of EM. TV's holding. Could that work to Mr. Ecctestone's advantage? Quite possibly. The lower the value of EM. TV's stake, the higher the relative value of an option Mr. Ecclestone holds to sell a further 25% of SLEC m EM. TV for around $1 billion--and the better the deal Mr. Ecclestone might be able to extract for surrendering the option. Whoever buys EM. TV's stake in SLEC will have to negotiate with Mr. Ecclestone over this instrument. The Economist understands that Mr. Ecclestone has the fight to veto a plan proposed last December by Kireh, a privately owned German media group, to buy half of EM. TV's holding for $550 million. In the coming weeks, Mr. Ecclestone will doubtless be deploying his formidable negotiating skills to best advantage. It would be hasty to bet against his securing a good deal out of EM. TV's difficulties. His dispute with the F1A may then be easily resolved. As usual, he holds all the cards.

单选题When stars like our Sun die, they bloat to become red giants and then eject gigantic clouds of gas and dust into space. Increasingly, however, scientists found themselves at a profound loss to explain how exactly dying stars could blow away these clouds. Now astrophysicists propose that unexpected chemical reactions during the formation of stardust could help solve this mystery. Stars smaller than the Sun and up to eight times as massive die by swelling up into red giants before shedding most of their mass to shrink into very compact, dying embers (灰烬) called white dwarfs. Two kinds of red giants exist-those with lots of carbon, and others richer in oxygen than in carbon. Carbon-rich stars release carbon particles during their death throes. Scientists proposed these pitch-black grains absorb rays from the dying star and get shot into space by starlight, a theory that fit both the observations and computer models. Increasingly, however, researchers could not explain how oxygen-rich stars like our own Sun could propel their clouds away during the final stages of mass loss. Oxygen-rich stars create large quantities of water vapor and silicates, such as quartz (石英砂) or sand. These are transparent, meaning starlight should go right through them. Possible solutions have been contemplated by scientists. They first pondered whether the silicates might have iron in them, which would render them opaque instead of transparent. But calculations showed the dust grains would have evaporated if they had iron in them. They next wondered if enough molecules surrounded the core of a dying oxygen-rich star to block out its light and thus create a wind that blew the star's outermost layer into space. But their models suggested these molecules could not block off enough light and create strong enough Rinds. The scientists then suggested that pulsations occurred when stars die could perhaps force a star's matter out, but this idea did not match with astronomers' observations. But inspiration then dawned upon them. Perhaps some of the carbon in the oxygen-rich stars could help force the outer layers of the stars into space. They believe shock waves from the pulsations of dying stars could make carbon in oxygen-rich stars form pitch-black dust. "The theory fits with all our subsequent model calculations, and it matches observations from dying oxygen-rich red giants". Moreover," this mechanism strongly favors the presence of magnesium silicates over iron silicates in the interstellar medium," in agreement with recent findings from NASA's comet-sampling Stardust space probe. If proven correct, the beauty of the new scenario is that it suggests a common driving mechanism for many dying stars shedding their mass via dusty winds," with possible long-reaching consequences for the origin of chemical elements relevant for life./

单选题Both Boeing and Airbus have trumpeted the efficiency of their newest aircraft, the 787 and A350 respectively. Their clever designs and lightweight composites certainly make a difference. But a group of researchers at Stanford University, led by Ilan Kroo, has suggested that airlines could take a more naturalistic approach to cutting jet-fuel use, and it would not require them to buy new aircraft. The answer, says Dr. Kroo, lies with birds. Since 1914, and a seminal paper by a German researcher called Carl Wieselsberger, scientists have known that birds flying in formation—a V-shape, echelon or otherwise—expend less energy. The air flowing over a bird's wings curls upwards behind the wingtips, a phenomenon known as upwash. Other birds flying in the upwash experience reduced drag, and spend less energy propelling themselves. Peter Lissaman, an aeronautics expert who was formerly at Caltech and the University of Southern California, has suggested that a formation of 25 birds might enjoy a range increase of 71%. When applied to aircraft, the principles are not substantially different. Dr. Kroo and his team modeled what would happen if three passenger jets departing from Los Angeles, San Francisco and Las Vegas were to rendezvous over Utah, assume an inverted V-formation, occasionally swap places so all could have a turn in the most favourable positions, and proceed to London. They found that the aircraft consumed as much as 15% less fuel (with a concomitant reduction in carbon-dioxide output). Nitrogen-oxide emissions during the cruising portions of the flight fell by around a quarter. There are, of course, kinks to be worked out. One consideration is safety, or at least the perception of it. Would passengers feel comfortable travelling in convoy'? Dr. Kroo points out that the aircraft could he separated by several nautical miles, and would not be in the unnervingly easy groupings favoured by display teams like the Red Arrows. A passenger peering out of the window might not even see the other planes. Whether the separation distances involved would satisfy air-traffic-control regulations is another matter, although a working group at the International Civil Aviation Organization has included the possibility of formation flying in a blueprint for new operational guidelines. It remains to be seen how weather conditions affect the air flows that make formation flight more efficient. In zones of increased turbulence, the planes' wakes will decay more quickly and the effect will diminish. Dr. Kmo says this is one of the areas his team will investigate further. It might also he hard for airlines to coordinate the departure times and destinations of passenger aircraft in a way that would allow them to gain from formation flight. Cargo aircraft, in contrast, might be easier to reschedule, as might routine military flights. As it happens, American's armed forces are on the ease already. Earlier this year the country's Defense Advanced Research Projects Agency announced plans to pay Boeing to investigate formation flight, though the programme has yet to begin. There are reports that some military aircraft flew in formation when they were low on fuel during the Second World War, hut Dr. Lissaman says they are apocryphal. "My father was an RAF pilot and my cousin the skipper of a Lancaster lost over Berlin," he adds. So he should know.