单选题The secret of his success is that he does everything efficiently .

单选题Elderly people easily become socially isolated .

单选题In the background was that {{U}}eternal{{/U}} hum

单选题Brain Train Millions of copies of console and computer- based" brain trainers" are sold worldwide every year, claiming to make peoples'brains younger, better, faster or bigger. The theory seems to make sense: regularly exercising the brain with tests and puzzles can improve brain skills and help people become better at everyday thinking tasks. But recent research suggests scientific evidence is lacking. The BBC's Brain Test Britain experiment wants to find out if brain training really works, and is aiming to get thousands of members of the public to train for 10 minutes a day ,three times a week ,for at least six weeks. Scientific experiments and their findings should be evaluated by independent experts in a process called "peer review". This is the minimum standard by which the quality of any research is judged. Very little research on commercial brain trainers has been peer reviewed. Instead, manufacturers often quote unsupported testimonials from" satisfied users". None of these are acceptable substitutes for peer review. A proper" control group" is the backbone of any valid scientific study. With a brain training study, the control group of participants should do the same amount of a mental activity as the brain - training group, but using a" non - brain training" activity such as a crossword. Scientists should then be able to compare the results from the two groups to see how genuinely effective the brain training tasks were. Studies that have been used to support the claims made by commercial brain trainers often have no control group at all, or a control group that is not as mentally active as the trained group. In order to see how much you have improved, you need to know where you were at the start. To do this. scientists use a" benchmarking test"—the same test, taken at the beginning and end of an experiment. Benchmarking tests should he different from the brain training tasks. This way, scientists can see if the effects of brain training are transferable to other mental tasks. Studies used to support the claims made by commercial brain trainers often use tests for benchmarking that are identical—or very similar—-to the tests used during training

单选题The National Park Service America"s national parks are like old friends. You may not see them for years at a time, but just knowing they"re out there makes you feel better. Hearing the names of these famous old friends—Yosemite, Yellowstone, Grand Canyon—revives memories of visits past and promotes dreams of those still to come. From Acadia to Zion, 369 national parks are part of a continually evolving system. Ancient fossil (化石的) beds, Revolutionary War battlefields, magnificent mountain ranges, and monuments to heroic men and women who molded this country are all a part of our National Park System (N. P. S.). The care and preservation for future generations of these special places is entrusted (托管) to the National Park Service. Uniformed Rangers, the most visible representatives of the Service, not only offer park visitors a friendly wave, a helpful answer, or a thought-provoking history lesson, but also are skilled rescuers, firefighters, and dedicated resource protection professionals (专业人员). The National Park Service ranks also include architects, historians, archaeologists, biologists, and a host of other experts who preserve and protect everything from George Washington"s teeth to Thomas Edison"s wax recordings. Modern society has brought the National Park Service both massive challenges and enormous opportunities. Satellite and computer technologies are expanding the educational possibilities of a national park beyond its physical boundaries. Cities struggling to revive their urban cores are turning to the Park Service for expert assistance to preserve their cultural heritage, create pocket parks and green spaces, and re-energize local economies. Growing communities thirsty for recreational outlets are also working with the NPS to turn abandoned railroad tracks into bike and hiking trails, as well as giving unused federal property new life as recreation centers. To help meet these challenges and take advantage of these opportunities, the National Park Service has formed partnerships—some dating back 100 years, some only months old--with other agencies, state and local governments, corporations, American Indian tribes and Alaska Natives, Park Friends groups, cooperating associations, private organizations and community groups.

单选题A research center has been set up in this country.A. praisedB. establishedC. reformedD. criticized

单选题 Cities "Worse to Live in Than 20 Years Ago"One thousand people were surveyed about a range of issues which affect cities, and the remarkable findings show that life in today's mega-cities is so stressful that at least two-thirds of those currently living in big cities would like to relocate to the countryside or a small town. The stress of the getting from A to B in big cities is at the top of the list of problems. For many people, the daily commute (通勤) to work is a source of frustration. 40% of the people in the survey have suffered from road rage while stuck in traffic on the way to work. The cost of public transport is also a serious problem. Many people think the price of underground and bus travel is too high and that they have to devote more than 10% of their salary to transport costs. The general cost of living in cities is another problem. The high property prices in most big cities put buying a property out of reach of most first-time buyers. Many young people are priced out of the housing market, and have to take in lodgers to make ends meet, or rent over-priced flats miles away from the city centre. In London, for instance, the price of buying even a one-bedroom flat is so prohibitive that many have given up even considering putting money aside for a deposit. Another issue facing people who live in cities is rising crime. Crime rates have rocketed in many big cities, and many say there are several dangerous no-go areas in their city. Fear of crime is on the increase— street crimes, such as mugging and assault, are now very common—and many are afraid of going out at night alone. Many were also concerned by the lack of green spaces and play facilities for children. Most major conurbations (有卫星城的大都市) surveyed have a far smaller number of parks and gardens than a generation ago. Planning permission seems to have been given for an ever-greater number of supermarkets, office developments and apartments on sites where there were previously green spaces. Many of the respondents in the survey said they felt stressed and suffocated (窒息) in the city, a problem which is compounded by pollution. And finally, the majority of people in the survey were fed up with the constant noise pollution—the roar of traffic, the sound of loud music blaring (发刺耳声) out of a neighbour's window, and the constant sound of activity. It is not surprising, then, that the levels of stress-related illnesses among people who live in cities are higher than ever before. Big cities, once a mecca (朝拜的地方) for ambitious people seeking fame and fortune, are now less and less popular among people of all ages. Perhaps the 21 st century is set to be the century of the small town and the countryside.

单选题After his military defeat in 1865,Robert E. Lee entreated the people of the South to work for national harmony.

单选题下面有3篇短文，每篇短文后有5道题，请根据短文内容，为每题确定1个最佳选项。 {{B}}第一篇{{/B}} Pool Watch Swimmers can drown in busy swimming pools when lifeguards(救生员) fail to notice that they are in trouble. The Royal Society for the Prevention of Accidents says that on average 15 people drown in British pools each year, but more suffer major injury after getting into difficulties. Now a French company has developed an artificial intelligence system called Poseidon that sounds the alarm when it sees someone in danger of drowning. When a swimmer sinks towards the bottom of the pool, the new system sends an alarm signal to a poolside(游泳池边) monitoring station and a lifeguard's pager. In trials(试验)at a pool in Ancenis, near Nantes, it saved a life within just a few months, says Alistair McQuade, a spokesman for its maker, Poseidon Technologies. Poseidon keeps watch through a network of underwater and overheard video cameras. AI software analyses the images to work out swimmers trajectories(轨道). To do this reliably, it has to tell the difference between a swimmer and the shadow of someone being cast onto the bottom or side of the pool. "The underwater environment. Is a very dynamic one, with many shadows and reflections dancing around, " says McQuade. The software does this by "projecting" a shape in its field of view onto an image of the far wall of the pool. It does the same with an image from another camera viewing the shape from a different angle. If the two projections are in the same position, the shape is identified as a shadow and is ignored. But if they are different, the shape is a swimmer and so the system follows its trajectory. "To pick out potential drowning victims, anyone in the water who starts to descend slowly is added to the software's "pre-alert" list," says McQuade. Swimmers who then stay immobile on the pool bottom for 5 seconds or more are considered in danger of drowning. Poseidon double-cheeks that the image really is of a swimmer, not a shadow, by seeing whether it obscures the pool's floor texture when viewed from overhead (在头顶上). If so, it alerts the lifeguard, showing the swimmer's location on a poolside screen. The first full-scale Poseidon system will be officially opened next week at a pool in High Wycombe, Buckinghamshire. One man who is impressed with the idea is Travor Baylis, inventor of the clockwork(时钟机构) radio. Baylis runs a company that installs swimming pools — and he was once an underwater escapologist (表演脱身术的人) with a circus. "I say full marks to them if this works and can save lives, " he says. But he adds that any local authority spending ￡30,000-plus on a Poseidon system ought to be investing similar amounts in teaching children to swim.

单选题Policing Skills In many ways, though, definition of such skills is quite unnecessary for an analysis of policing. It is really most unlikely that the average police officer will ever in his career perform or even witness those detective skills that he has enjoyed in countless TV products. The reason for this is simply that the vast majority of crimes are usually either very likely to be solved by routine investigation or they are very unlikely to be solved at all. Fortunately, the clear - up rate for serious crimes tends to be very high. Zander( 1979 )has shown why. In his study of Old bailey cases ,the identity of the defendant(被告) seems to have been reasonably clear in 87% of cases. Morgan (1980 and ongoing)has shown that well over 92% of crimes known to the police are discovered by the public who provide the majority of decisive information. In Morgan's study, crimes that were" solved" contained in their crime files over twice the amount of qualitative information as crimes that were not" solved". The various bits of information in value in terms of probability of detection, "solving" of the crime. In this, where information was provided by the public during a police interview, the information was believed to the police" since it was felt that in an interview genuine police skills are involved in the collection of information. "Evidently this method can be justified thus, but will necessarily overestimate the police role. Nevertheless, in this analysis of crime files it was shown that in cases where crimes were solves, the public still provided nearly twice the amount of information as the police.

单选题We packed up the things we had accumulated (积累) over the last three years and left.

单选题The microscope enables scientists to distinguish an incredible number and variety of bacteria.

单选题Woman work Though some people have suggested that women should return to housework in order to leave (51) jobs for men, the idea has been rejected by both women and men in public (52) polls. Lately some union officials have suggested that too many women are employed in types of work more (53) for men and that women should step aside to make way for unemployed young men. They argue that women, especially women in their childbearing years, (54) delay economic development and result in productivity, poor quality and inefficiency. To solve the problem, they suggested that working women stay at home (55) their husbands or brothers were given double wages. They argue that (56) these circumstances, families would (57) their same level of income, and women could run the house and (58) children much better. The suggestion, (59) , has been flatly rejected by 9 out of 10 people (60) Some other people have suggested another way (61) "phased employment" theory. The theory suggests that a woman worker take (62) from her job when she is seven months pregnant and stay off the job (63) her baby reaches the age of 3. It suggested that women on leave receive 75 percent of their (64) . salary and be allowed to return to work after the three-year period. This will (65) children, women, their families and the society and it definitely seems to be more acceptable than the suggestion that women return to their homes forever.

单选题Their business {{U}}flourished{{/U}} at its new location a year later owing to their joint efforts and hard work. A. prevailed B. failed C. boomed D. shrank

单选题We shall keep the money in a secure place.

单选题I enjoyed the play; it had a clever plot and very funny dialogues.

单选题Less Is More It sounds all wrong—drilling holes in a piece of wood to make it more resistant to knocks. But it works because the energy from the blow gets distributed throughout the wood rather than focusing on one weak spot. The discovery should lead to more effective and lighter packaging materials. Carpenters have known 1 centuries that some woods are tougher than others. Hickory (山核桃木), for example, was turned into axe handles and cartwheel spokes (轮辐) because it can absorb shocks without breaking. White oak, for example, is much more easily damaged, 2 it is almost as dense. Julian Vincent at Bathe University and his team were convinced that the wood"s internal structure could explain the differences. Many trees have tubular (管状的) vessels that run 3 the trunk and carry water to the leaves. In oak they are large, and arranged in narrow bands, but in hickory they are smaller, and more evenly distributed. The researchers 4 this layout might distribute a blow"s energy throughout the wood, soaking up a bigger hit. To test the idea, they drilled holes 0.65 millimetres across into a block of spruce (云杉), a wood with 5 vessels, and found that 6 withstood a harder knock. 7 when there were more than about 30 holes per square centimetre did the wood"s performance drop off. A uniform substance doesn"t cope well with knocks because only a small proportion of the material is actually 8 . All the energy from the blow goes towards breaking the material in one or two places, but often the pieces left 9 are pristine (未经破坏的). But instead of the energy being concentrated in one place, the holes provide many weak spots that all absorb energy as they break, says Vincent. "You are controlling the places 10 the wood breaks, and it can then absorb more 11 , more safely." The researchers believe the principle could be applied to any material— 12 example, to manufacture lighter and more protective packaging. It could 13 be used in ear bumpers, crash barriers and armour for military vehicles, says Ulrike Wegst, a 14 at the Max Plank Institute for Mental Research in Stuttgart. But she emphasizes that you 15 to design the substance with the direction of force in mind. "The direction of loading is crucial," she says.

单选题 阅读下面的短文，文中有15处空白，每处空白给出了4个选项，请根据短文的内容从4个选项中选择1个最佳答案。 {{B}} Migrant (移民的) Workers{{/B}} In the past twenty years, there has been an increasing tendency for workers to move from one country to another. While some countries have restricted most{{U}} (51) {{/U}}to local people, others have attracted and welcomed migrant workers. This is particularly the case in the Middle East,{{U}} (52) {{/U}}increased oil incomes have enabled many countries to call in outsiders to improve local facilities. Thus the Middle East has attracted oil-workers{{U}} (53) {{/U}}the .U.S.A. and Europe. It has brought in workers from many countries,{{U}} (54) {{/U}}South Korea and Japan. In view of the difficult living and working{{U}} (55) {{/U}}in the Middle East, it is not surprising that the pay is high to attract suitable workers. Many engineers and technicians can{{U}} (56) {{/U}}at least twice as much money in the Middle East as they can in their own country, and this is a major{{U}} (57) {{/U}}. Sometimes a disadvantage has a compensating (补偿) advantage. For example, the{{U}} (58) {{/U}}living conditions often lead to increased friendship when workers have to{{U}} (59) {{/U}}on each other for safety and comfort. In a similar way, many migrant workers can save large sums of money partly because of the{{U}} (60) {{/U}}of entertainment facilities. The work is often complex and full of problems but this merely{{U}} (61) {{/U}}greater challenge to engineers who prefer to find solutions to problems rather than do routine work in their home country. One major problem which{{U}} (62) {{/U}}migrant workers in the Middle East is that their jobs are temporary ones. They are nearly always on{{U}} (63) {{/U}}, so it is not easy for them to plan ahead with great confidence. This is to be{{U}} (64) {{/U}}since no country welcomes a large number of foreign workers as permanent residents. In any{{U}} (65) {{/U}}, migrant workers accept this disadvantage, along with others, because of the considerable financial benefits which they receive.

单选题California—a Land of Variety and Contrast California is a land of variety and contrast. Almost every type of physical land feature, sort of arctic ice fields and tropical jungles can be found within its borders. Sharply contrasting types of land often lie very close to one another. People living in Bakersfield, for instance, can visit the Pacific Ocean, the coastal plain, the fertile San Joaquin Valley, the arid Mojave Desert, and the high Sierra Nevada, all within a radius of about 100 miles. In other areas it is possible to go snow skiing in the morning and surfing in the evening of the same day, without having to travel long distance. Contrast abounds in California. The highest point in the United States (outside Alaska) is in California, and so is the lowest point (including Alaska). Mount Whitney, 14,494 feet above sea level, is separated from Death Valley, 282 feet below sea level, by a distance of only 100 miles. The two areas have a difference in altitude of almost three miles. California has deep, clear mountain lakes like Lake Tahoe, the deepest in the country, but it also has shallow, salty desert lakes. It has Lake Tulainyo, 12,020 feet above sea level, and the lowest lake in the country, the Salton Sea, 236 feet below sea level. Some of its lakes, like Owens Lake in Death Valley, are not lakes at all: they are dried up lake beds. In addition to mountains, lakes, valleys, deserts, and plateaus, California has its Pacific coastline, stretching Longer than the coastlines of Oregon and Washington combined.

单选题Which of the following is a long-established practice in the opening ceremony?