单选题These are our motives for doing it.

单选题Things have changed a lot since I was a child.A. graduallyB. suddenlyC. greatlyD. frequently

单选题第一篇 Hair Detectives Scientists have found a way to use hair to figure out where a person is from and where that person has been. The finding could help solve crimes, among other useful applications. Water is central to the new technique. Our bodies break water down into its parts: hydrogen(氢) and oxygen. Atoms(原子) of these two elements end up in our tissues and hair. But not all water is the same. Hydrogen and oxygen atoms can vary in how much they weigh. Different forms of a single element are called isotopes(同位素). And depending on where you live, tap water contains unique proportions of the heavier and lighter isotopes of hydrogen and oxygen. Might hair record these watery quirks(古怪举动；怪癖). That"s what James R. Ehleringer, an environmental scientist at the University of Utah in Salt Lake City, wondered. To find out, he and his colleagues collected hair from barbers and hair stylists(发型师) in 65 cities in 18 states across the United States. The researchers assumed that the hair they collected came from people who lived in the area. Even though people drink a lot of bottled water these days, the scientists found that hair overwhelmingly(压倒性地) reflected the concentrations of hydrogen and oxygen isotopes in local tap water. That"s probably because people usually cook their food in the local water. What"s more, most of the other liquids people drink including milk and soft drinks contain large amounts of water that also come from sources within their region. Scientists already knew how the composition of water varies throughout the country. Ehleringer and colleagues combined that information with their results to predict the composition of hair in people from different regions. One hair sample used in Ehleringer"s study came from a man who had recently moved from Beijing,China, to Salt Lake City. As his hair grew, it reflected his change in location. The new technique can"t point to exactly where a person is from, because similar types of water appear in different regions that span a broad area. But authorities can now use the information to analyze hair samples from criminals or crime victims and narrow their search for clues(线索).

单选题{{U}}Accordingly{{/U}}, a number of other methods have been employed.

单选题The nursery is bright and cheerful. A. pleasant B. colorful C. fashionable D. different

单选题Sleep Now, Remember Later How sleep helps US consolidate memories is still largely a mystery. A recent study from the University of Liibeck, in Germany, offers one clue-Subjects were given a list of 46 word pairs to memorize, just before sleep. Then when they reached the deepest stages of sleep, electrical currents were sent through electrodes on their" heads to induce very slow brain waves. Such slow waves were induced at random in the brains of one group of subjects, but not another. The next morning, the slow-wave group had better recall of the words. Other types of memory were no| improved, and inducing the slow waves later in the night did not have the same eftect. Why and how the slow waves improved memory is not yet understood, but they are thought to alter the strengths of chemical connections, or synapses, between specific pairs of nerve cells in the brain. Memories are "stored" in these synapses: changing the strength of the synapses increases the strength of the memories they store. It's not just memory that is improved by sleep. Recent studies indicate that sleep riot only helps store facts, it also helps make connections between them. Ullrich Wagner arid colleagues in Germany used a puzzle in which players were given a string of numbers, and required to make a series of seven calculations based on these numbers. The seventh calculation (which depended on the preceding six) was the" answer. "Participants repeatedly played the same game with the same roles, but different sets of numbers. The researchers structured the game such that the second calculation always gave the same answer as the seventh calculation-the final answer. If players recognized this rule, they could get to the final answer much faster. Sonic of the players played the game in the morning, then did other things for eight hours or so, then played the game again. Others played the game first in the evening, then slept, then played it again alter awakening. The players who slept were almost three times more likely to have the insight that allowed them to spot the rule. Why is this important? Some sleep researchers believe that for every two hours we spend awake, the brain needs an hour of sleep to figure out what all these experiences mean, and that sleep plays a crucial role in constructing the meaning our lives come to hold. Breakdowns in such sleep-dependent processing may contribute to the development of depression, and may explain why some people who experience horrific traumas go on to develop post-traumatic stress disorder.

单选题The government has {{U}}put forward{{/U}} new proposals to tackle the problem of increasing crime.

单选题 Sonic Device The other day, Dr. Robert Smith, who is blind, took a remarkable stroll through the campus of the University of California at Santa Barbara. As Dr. Smith walked along the campus, places and impediments (障碍物) in his path seemed to call out their names to him, "library here, library here", "bench here, bench here". Dr. Smith was testing a prototype (样机) navigation system for the blind that announced the surrounding objects through stereo headphones that were mounted to a computer in his back-pack (背包), creating virtual reality landscape (仿真景象). The information came not from some miniature radar but from the signals broadcast by the military's network of global positioning satellites (全球定位卫星). One day, its developers hope, miniaturized (小型化的) versions of this navigation device, which now weighs 28 pounds, will help the blind navigate unfamiliar neighborhoods. "With this system you do not need to know a thing in advance about where you are going," said Dr. Roberta Klatzky, a psychologist at Carnegie Mellon University who is working with Dr. Smith to develop the navigating device. Dr. Michael Oberdor of the National Eye Institute said, "A blind person could walk down the street and know not just that he was at 80th and Broadway, but what stores are around, and that Zabar's delicatessen (熟食店) was up ahead. This navigation system tells you not just where there are obstacles, but your overall location geographically." It lets blind users construct a mental map of new surroundings and learn their way around. The navigation system uses signals from a computerized map to create a "virtual acoustic display (仿真声音显示)". This is a talking map in which large objects seem to announce themselves in the headphones with the precise timing and loudness that would be the case if the objects were actually making a sound. This allows the blind person to sense immediately his or her distance or direction, and use that information for guidance. While no one knows whether it is because blind people tend to develop a sharper sense of hearing. Those who have tried the system say that they quickly adapt to locating an object through the sounds. "One of the crucial features of this system is that it takes advantage of sensory psychophysics (感官心理物理学)—how the brain interprets signals from outside to make a map of your surroundings so you can navigate," Dr. Oberdor said.

单选题{{B}}第二篇{{/B}} {{B}} The Development of PR{{/B}} The rise of multinational corporations, global marketing, new communications technologies, and shrinking cultural differences have led to an unparalleled increase in global public relations or PR. Surprisingly, since modern PR was largely an American invention, the U. S. leadership in public relations is being threatened by PR efforts in other countries. Ten years age, for example, the world’s top five public relations agencies were American-owned. In 1991, only one was. The British in particular are becoming more sophisticated and creative. A recent survey found that more than half of all British companies include PR as part of their corporate planning activities, compared to about one-third of U. S. companies. It may not belong before London replaces New York as the capital of PR. Why is America lagging behind in the global PR race? Firstly, Americans as a whole tend to be fairly provincial and take more of an interest in local affairs. Knowledge of world geography, for example, has never been strong in this country. Secondly, American lag behind their European and Asian counterparts in knowing a second language. Less than 5 percent of Bur son-Marshall’s U.S. employees know two languages. Ogilvy and Mather has about the same percentage. Conversely, some European firms have half or more of their employees fluent in a second language. Finally, people involved in PR abroad tend to keep a closer eye on international affairs. In the financial PR area, for instance, most Americans read the Wall Street Journal. Overseas, their counterparts read the Journal as well as the Financial Times of London and The Economist, publications not often read in this country. Perhaps the PR industry might take a lesson from Ted Turner of CNN (Cable News Network). Turner recently announced that the word “foreign” would no longer be used on CNN news broadcasts. According to Turner, global communications have made the nations of the world so interdependent that there is no longer any such thing as foreign.

单选题The dentist has decided to extract her bad tooth. A．take out B．repair C．push in D．dig

单选题What does the writer want to tell in the passage?

单选题The attitude of the author towards the research project is

单选题第二篇 Pushbike Peril Low speed bicycle crashes can badly injure or even kill children if they fall onto the ends of the handlebars(车把) so a team of engineers is redesigning the humble handlebar in a bid to make it safer. Kristy Arbogast, a bioengineer at the Children"s Hospital of Philadelphia in Pennsylvania, began the project with her colleagues after a study of serious abdominal(腹部的) injuries in children in the past 30 years showed that more than a third were caused by bicycle accidents. "The task was to identify how the injuries occurred and come up with some countermeasures(对策)." she says. By interviewing the children and their parents, Arbogast and her team were able to reconstruct(重建；重构) many of the accidents and identified a common mechanism responsible for serious injures. They discovered that most occur when children hit an obstacle at a slow speed, causing them to topple over. To maintain their balance they turn the handlebars through 90 degrees, but their momentum (冲力) forces them into the end of the handlebars. The bike then falls over and the other end of the handlebars hits the ground, ramming it into their abdomen. The solution the group came up with is a handgrip(握柄) fitted with a spring and damping(制动的；减速的，缓冲的)system. The spring absorbs up to 50 percent of the forces transmitted through the handlebars in an impact. The group hopes to commercialize(使商品化) the device, which should add only a few dollars to the cost of a bike. "But our task has been one of education because up until now, bicycle manufacturer were unaware of the problem." says Arbogast. The team has also approached the US Consumer Product Safety Commission to try to persuade manufacturers to adopt the new design. A decision is expected later this year.

单选题New Product Will Save lives Drinking water that looks clean may still contain bugs (虫子), which can cause illness. A small company called Genera Technologies has produced a testing method in three stages, which shows whether water is safe. The new test shows if water needs chemicals added to it, to destroy anything harmful. It was invented by scientist Dr. Adrian Parton, who started Genera five years ago. He and his employees have developed the test together with a British water company. Andy Headland, Genera's marketing director, recently presented the test at a conference in the USA and forecast good American sales for it. Genera has already sold 11 of its tests at $42,500 a time in the UK and has a further four on order. It expects to sell another 25 tests before the end of March. The company says it is the only test in the UK to be approved by the government. Genera was formed five years ago and until October last year had only five employees; it now employs 14. Mr Headland believes that the company should make around $19 million by the end of the year in the UK alone.

单选题I don't feel secure when I am alone in the house.A. safeB. prettyC. distantD. obvious

单选题I did not realize the actual seriousness of the environmental problem.A. extremeB. generalC. detailedD. practical

单选题______ more time, my paper would have been better.A. to giveB. if givingC. givenD. giving

单选题By referring to computers and other inventions, the author means to say that future achievements in technology will bring about inconceivable dramatic changes.

单选题Mary is looking for the book she lost yesterday. A. trying to find B. trying to read C. trying to buy D. trying to borrow

单选题During the Second World War, all important resources in the U.S. were allocated by the federal government.A. distributedB. nationalizedC. commandeeredD. taxed