单选题The tomato juice left brown______on the front of my jacket. A. spot B. point C. track D. trace

单选题The very sight of the imposing buildings assured these tourists of the significant changes in this city.

单选题The change in Japanese life - style is revealed in the fact that ______.

单选题The guides ______ the tourists together at the hotel gate.

单选题The primary aim of some companies' sponsoring the search engines is to ______.

单选题Changes in climate ______ slowly through the years.

单选题Mr.Brownissupposedto __________ forItalylastmonth.

单选题"The impulse to excess among young Britons remains as powerful as ever, but the force that used to keep the impulse in check has all but disappeared," claimed a newspaper. Legislation that made it easier to get hold of a drink was "an Act for the increase of drunkenness and immorality", asserted a politician. The first statement comes from 2005, the second from 1830. On both occasions, the object of scorn was a parliamentary bill that promised to sweep away " antiquated" licensing laws. As liberal regulations came into force this week, Britons on both sides of the debate unwittingly followed a 19th-century script. Reformers then, as now, took a benign view of human nature. Make booze cheaper and more readily available, said the liberalisers, and drinkers would develop sensible, continental European-style ways. Nonsense, retorted the critics. Habits are hard to change; if Britons can drink easily, they will drink more. Worryingly for modern advocates of liberalisation, earlier doomsayers turned out to be right. Between 1820 and 1840, consumption of malt (which is used to make beer) increased by more than 50%. Worse, Britons developed a keener taste for what Thomas Carlyle called "liquid madness"—gin and other spirits. The backlash was fierce. Critics pointed to widespread debauchery in the more disreputable sections of the working class. They were particularly worried about the people who, in a later age, came to be known as "ladettes". An acute fear, says Virginia Berridge, who studies temperance at the London School of Hygiene and Tropical Medicine, was that women would pass on their sinful ways to their children. In the 19th century, temperance organisations set up their own newspapers to educate the public about the consequences of excess. That, at least, has changed: these days, the mainstream media rail against the demon drink all by themselves.

单选题 Although the top men in smuggling business must work together, most of a syndicate's small fry, specially the mules, know only their immediate contacts. If caught there is little they can give away. A mule probably will not even know the name of the person who gives him his instructions, nor how to get in touch with him. Usually he even does not know the person to whom he has to make delivery. He will be told just to sit tight in a certain hotel or bar until someone contacts him. In this way if he is blown, coming through airport customs he cannot unwittingly lead agents to the next link in the chain. All that the person at the receiving end do is to hang around the airport among the waiting crowd, and see that the mule comes through safely. If he does not, he is dimply written off as a loss. To make identification of mules easier, several syndicates have devised their own 'club ties' so that a mule wearing one can immediately be picked out. Mules often receive careful training before embarking on their first journey. One Beirut organization, for example, uses a room with three airline seats in it. There the trainee mules sit for hours on end wearing weighted smuggling vests beneath their clothes, so that they become accustomed to standing up after a long flight in a natural way, and without revealing what they are carrying. An outfit in Brussels maintained a comfortable apartment where the mules could relax and get a firm grip on themselves on the night before their first journey; they were helped to dress before setting out for the airport in the morning. More often than not a courier will not know precisely where he is going or what flight number is until he is actually handed his tickets at the airport. This prevents the careless boast in some bar or to a girl friend the night before. Mules occasionally run off with the goods to keep the profit themselves. As insurance against this, a syndicate often sends a high-up on the same plane to keep a wary eye on couriers, particularly new ones. Even then things can go badly wrong. One international currency smuggler who was having trouble getting money out of Britain was offered help by a group of men who said they were in a position to 'fix thing'—for a fee of course. Foolishly, the smuggler agreed to accept their help. When he got to London's Heathrow Airport, he handed over to one of the men a black suitcase containing nearly $90,000 in cash, destined for Frankfurt. Just to keep an eye on things, the smuggler went along on the same plane. When they landed at Frankfurt he was handed back his suitcase. He beat a straight path to the men's toilet, opened the case, and found only old clothes. The courier had switched suitcase en route, but the smuggler could hardly run to the police and complain that 'the man who was smuggling money out of England for me has stolen it.'

单选题Community cancer clusters are viewed quite differently by citizen activists than by epidemiologists. Environmentalists and concerned local residents, for instance, might immediately suspect environmental radiation as the culprit when a high incidence of cancer cases occurs near a nuclear facility. Epidemiologists, in contrast, would be more likely to say that the incidences were "inconclusive" or the result of pure chance. And when a breast cancer survivor, Lorraine Pace, mapped 20 breast cancer cases occurring in her West Islip, Long Island, community, her rudimentary research efforts were guided more by hope that a specific environmental agent could be correlated with the cancers than by scientific method. When epidemiologists study clusters of cancer cases and other noncontagious conditions such as birth defects or miscarriage, they take several variables into account, such as background rate (the number of people affected in the general population), cluster size, and specificity (any notable characteristics of the individual affected in each case). If a cluster is both large and specific, it is easier for epidemiologists to assign blame. Not only must each variable be considered on its own, but it must also be combined with others. Lung cancer is very common in the general population. Yet when a huge number of cases turned up among World War II shipbuilders who had all worked with asbestos, the size of the cluster and the fact that the men had had similar occupational asbestos exposures enabled epidemiologists to assign blame to the fibrous mineral. Although several known carcinogens have been discovered through these kinds of occupational or medical clusters, only one community cancer cluster has ever been traced to an environmental cause. Health officials often discount a community's suspicion of a common environmental cause because citizens tend to include cases that were diagnosed before the afflicted individuals moved into the neighborhood. Add to this the problem of cancer's latency. Unlike an infectious disease such as cholera, which is caused by a recent exposure to food or water contaminated with the cholera bacterium, cancer may have its roots in an exposure that occurred 10 to 20 years earlier. Do all these caveats mean that the hard work of Lorraine Pace and other community activists is for nothing? Not necessarily. Together with many other reports of breast cancer clusters on Long Island, the West Islip situation highlighted by Pace has helped epidemiologists lay the groundwork for a well designed scientific study.

单选题 In the Sierra Madre mountain range of west central Mexico, the native Huichol people live much the way their ancestors did—without electricity. That's because it's too expensive to string power lines to the remote mountain areas where they live. To help support themselves, the Huichol create beautiful artwork. They sell their art in cities hundreds of miles away from their villages. And without electricity—at home or on the road, they can only work during daylight hours. When it gets dark, they must stop whatever they're doing. Now, a team of scientists, designers, and architects is using new technologies to provide the Huichol with light after the sun sets. The scientists' technique involves weaving tiny electronic crystals into fabrics that can be made into clothes, bags, or other items. By collecting the sun's energy during the day, these lightweight fabrics provide bright white light at night. Their inventors have named the fabrics 'Portable Lights'. Portable Lights have the potential to transform the lives of people without electricity around the world, says project leader Sheila Kennedy. 'Our invention,' Kennedy says, 'came from seeing how we could transform technology we saw every day in the United States and move it into new markets for people who didn't have a lot of money.' At the core of Portable Light technology are devices called high-brightness light-emitting diodes, or HB LEDs. These tiny lights appear in digital clocks, televisions, and streetlights. LEDs are completely different from the light bulbs. Most of those glass bulbs belong to a type called incandescent lights. Inside, electricity heats a metal coil to about 2,200 degrees Celsius. At that temperature, bulbs give off light we can see. Ninety percent of energy produced by incandescent lights, however, is heat—and invisible. With all that wasted energy, bulbs burn out quickly. They are also easily broken. LEDs, on the other hand, are like tiny pieces of rock made up of molecules that are arranged in a crystal structure. When an electric current passes through an LED, the crystal structure produces light. Unlike incandescent bulbs, they can produce light of various colors. Within an LED, the type of molecules and their particular arrangement determine what color is produced.

单选题I've attached my contact information in the recommendation letter ______you have further questions. A. for good B. in order C. for fear D. in case

单选题In our highly technological society, the number of jobs for unskilled workers is ______.

单选题The babies would "smile and bubble" at the lights because ______.

单选题What has brought so many problems to Tokyo today?

单选题Mr. Wang and his son, both looking very happy, ______ taking a walk in the park.

单选题The dictionary is shabbily compiled. What makes up somehow is the ______ it encloses.

单选题A national debate is now ______ about whether we should replace golden weeks with paid vacations. A. in the way B. by the way C. under way D. out of the way

单选题If you want to borrow books about American history, which floor would you go to? ______.

单选题此题为音频题