单选题 Nanotechnology Many of the grand challenges of today and the future are found in the question: "How are we going to solve the problems and make serious improvements in industrial manufacturing, disease control, environmental pollution control, global climate change, food production, transportation, communication, and others?" Nanotechnology (纳米技术) promises to make revolutionary contributions. Within the next few years we can expect to see major improvements. Here are some possibilities the things to come. Nanotechnology is fundamentally changing the way materials and devices will be produced in the future. Nanostructures, ceramics, polymers, metals, and other materials will have greatly improved mechanical properties. In fact, with the ability to build things atom-by-atom and molecule-by-molecule there will be new classes of structural materials. Nanotechnology will enable products to be lighter, stronger, smarter, cheaper, cleaner, and more precise. The ability to synthesize nanoscale budding blocks with precisely controlled size and composition and then to assemble them into larger structures with unique properties and functions will revolutionize segments of the materials manufacturing industry. Nanotechnology is expected to bring about lighter, stronger, and programmable materials; reductions in life-cycle costs through lower failure rates; innovative devices based on new principles and architectures; and use of molecular cluster manufacturing. Nanotechnology will provide new tools for medicine. It could radically change the way surgery is done. It will make it possible to do molecular scale surgery to repair and rearrange cells. Since disease is the result of physical disorder, misarranged molecules and cells, medicine at this level should be able to cure most diseases. Mutations in DNA could be repaired and cancer cells, toxic chemicals, and viruses could be destroyed through use of medical Nan devices. Nanotechnology enabled increases in computational power will permit the characterization of macromolecular networks in realistic environments. Such simulations will be essential elements in the development of biocompatible implants and in the drug discovery process. Nanotechnology has the potential to significantly impact energy efficiency, storage, and production. Nanotechnology can change the economics of energy production.

单选题Many new chances will be opened up in the future for those with a university education.

单选题Insects thrive all over, from the hottest deserts to the snow-clad peaks of lofty mountains.

单选题The phrase "make room" in the last paragraph could be best replaced by

单选题Eat More, Weigh Less, Live Longer Clever genetic detective work may have found out the reason why a near starvation diet prolongs the life of many animals. Ronald Kahn at Harvard Medical School in Boston, U.S., and his colleagues have been able to extend the lifespan of mice by 18 per cent by blocking the rodent's increase of fat in specific cells. This suggests that thinness and hot necessarily diet promotes long life in "calorie restricted" animals. "It's very cool work." says aging researcher Cynthia Kenyon of the University of California, San Francisco. "These mice eat all they want, lose weight and live longer. It's like heaven." Calorie restriction dramatically extends the lifespan of organisms as different as worms and rodents. Whether this works in humans is still unknown, partly because few people are willing to submit to such a strict diet. But many researchers hope they will be able to trigger the same effect with a drug once they understand how less food leads to a longer life. One theory is that eating less reduces the increase of harmful things that can damage cells. But Kahn's team wondered whether the animals simply benefit by becoming thin. To find out they used biology tricks to disrupt the insulin (胰岛素) receptor (受体) gene in lab mice but only in their fat cells. "Since insulin is needed to help fat cells store fat, these animals were protected against becoming fat," explains Kahn. This slight genetic change in a single tissue had dramatic effects. By three months of age, Kahn's modified mice had up to 70 percent less body fat than normal control mice, despite the fact that they ate 55 percent more food per gram of body weight. In addition, their lifespan increased. The average control mouse lived 753 days, while the thin rodents averaged a lifespan of 887 days. After three years, all the control mice had died, but one-quarter of the modified rodents were still alive. "That they get these effects by just manipulating the fat cells is controversial," says Leonard Guarente of the Massachusetts Institute of Technology, who studies calorie restriction and aging. But Guarente says Kahn has yet to prove that the same effect is responsible for increased lifespan in calorie restricted animals. "It might be the same effect or there might be two routes to long life," he points out, "and that would be very interesting./

单选题Psychologists think of attitudes as being {{U}}predispositions{{/U}} toward objects or events that determine the way people react to different stimuli.

单选题Feast On Turkey and Good Wishes at Thanksgiving Four weeks ago US children dressed as monsters and asked for sweets. That was Halloween. In a few weeks American houses will be red and green and filled with presents for Christmas. As if all this isn't enough, on Thursday this week, America will enjoy another festival— Thanksgiving. Children will have two days off school, shops will close and houses will be filled with families enjoying mountains of food. Every year, in Gainesville, Florida, all entire class celebrate Thanksgiving together. The class dresses up and puts on plays for their families. After the plays the families share a feast of traditional Thanksgiving foods like turkey and pumpkin pie. Dean Foster, an 11-year-old boy will take part in this celebration. He said, "I love Thanksgiving because it means time off school, lots of nice food and a happy family." His brother Ben, nine, said, "the best thing about Thanksgiving, is that when it is finished, it is time to start Christmas." But behind the food and the large amount of money spent there is another message. On Thursday evening, Dean and Ben's family will make a basket and put it on the table as they eat their evening meal. Each of them will write a list of things that they are thankful for and place the paper in the basket. The family will read the pieces of paper and take time to thank God and each other for providing them with comfortable and happy lives. Thanksgiving is a traditional festival that started in 1621, when the first pilgrims arrived in the US to start a new life. After a hard year, they had a big autumn harvest. They held a feast and invited the native American Indians along to thank God for giving them enough food. Many countries celebrate Thanksgiving. They often fall after the fields have been harvested and the crops collected for winter. turkey n. ,y,火鸡 pumpkin n. 南瓜 pilgrim n. 朝圣者 Thanksgiving ,感恩节(11月的第四个星期四) Halloweenl0月31日.之夜(据传此时可见到鬼) Christmas 圣诞节(12月25日)

单选题Anthropologists believe that in the sixteenth century a few thousand Inuits {{U}}inhabited{{/U}} northern Canada.

单选题The interpretation is faulty.A. wrongB. ambiguousC. unclearD. unbelievable

单选题It is absurd to predict that the sun will not rise tomorrow.

单选题Mary is{{U}} looking for{{/U}} the book she lost yesterday

单选题The passage mentions all of the following factors for the existence of life EXCEPT

单选题Milosevic"s Death Former Yugoslav leader Slobodan Milosevic was found dead last Saturday in his cell at the Hague-based International Criminal Tribunal for the former Yugoslavia. The 64-year-old had been on trial there since February 2002. Born in provincial Pozarevac in 1941, he was the second son of a priest and a school teacher. Both of his parents died when he was still a young adult. The young Milosevic was "untypical", says Slavoljub Djukic, his unofficial biographer. He was "not interested in sports, avoided excursions(短途旅行)and used to come to school dressed in the old-fashioned way-white shirt and tie." One of his old friends said, he could "imagine him as a station-master or punctilious(一丝不苟的)civil servant." Indeed that is exactly what he might have become, had he not married Mira. She was widely believed to be his driving force. At university and beyond he did well. He worked for various firms and was a communist party member. By 1986 he was head of Serbia"s Central Committee. But still he had not yet really been noticed. It was Kosovo that gave him his chance. An autonomous province of Serbia, Kosovo was home to an Albanian majority and a Serbian minority. In 1989, he was sent there to calm fears of Serbians who felt they were discriminated against. But instead he played the nationalist card and became their champion. In so doing, he changed into a ruthless(无情 的)and determined man. At home with Mira he plotted the downfall of his political enemies. Conspiring(密谋)with the director of Serbian TV, he mounted a modern media campaign which aimed to get him the most power in the country. He was elected Serbian president in 1990. In 1997, he became president of Yugoslavia. The rest of the story is well-known: his nationalist card caused Yugoslavia"s other ethnic groups to fight for their own rights, power and lands. Yugoslavia broke up when four of the six republics declared independence in 1991. War started and lasted for years and millions died. Then Western countries intervened. NATO bombed Yugoslavia, and he eventually stepped down as state leader in 2000. Soon after this, Serbia"s new government, led by Zoran Djindjic, arrested him and sent him to face justice at the Yugoslav war crimes tribunal in the Hague.

单选题She is always diplomatic when she deals with naughty students.

单选题The proposal provoked widespread criticism.

单选题Your plan about this project is excellent.A. outstandingB. wonderfulC. rareD. so-so

单选题The United States is a sports - loving nation. Sports in America take a variety of forms : organized competitive struggles, which draw huge crowds to cheer their favorite team to victory; athletic games, played for recreation anywhere sufficient space is found; and hunting and fishing. Most sports are seasonal, so that what is happening in sports depends upon the time of year. Some sports are called spectator sports, as the number of spectators greatly exceeds the number playing is the game. In the United States ,people enjoy all the following sports EXCEPTA. organized competitive struggles.B. athletic games.C. hunting and fishing.D. mountain climbing and bicyclin

单选题There is an abundant supply of cheap labor in this country.A. a steadyB. a plentifulC. an extraD. a stable

单选题Step Back in Time Do you know that we live a lot longer now than the people who were born before us? One hundred years ago the average woman lived to be 45. But now, she can live until at least 80. One of the main reasons for people living longer is that we know how to look after ourselves better. We know which foods are good for US and what we have to eat to make sure our bodies get all the healthy things they need. We know why we sometimes get ill and what to do to get better again. And we know how important it is to do lots of exercise to keep our hearts beating healthily. But in order that we don"t slip back into bad habits, let"s have a look at what life was like 100 years ago. Families had between 15 and 20 children, although many babies didn"t live long. Children suffered from lots of diseases, especially rickets (佝偻病) and scurvy (坏血病), which are both caused by bad diets. This is because many families were very poor and not able to feed their children well. Really poor families who lived in crowded cities like London and Manchester often slept standing up, bending over a piece of string, because there was no room for them to lie down. People didn"t have fridges until the 1920s. They kept fresh food cold by storing it on windowsills (窗台板), blocks of ice, or even burying it in the garden. Some children had to start work at the age of seven or eight 1o earn money for their parents. If you had lived 100 years ago, you might well be selling matchsticks (火柴杆) (a job done by many children) or working with your dad by now.

单选题They are worded about their Ucapacity/U to invest in the future.