单选题The outlook from the top of the mountain is breathtaking.

单选题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 (压倒性的) 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The weather was crisp and clear and you could see the mountains fifty miles away.　　A. fresh　　B. hot　　C. heavy　　D. windy

单选题"I'm not meddling," Mary said Umildly/U. "I'm just curious."

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}}Vienna{{/B}} Vienna was one of the music centers of Europe during the classical period, and Haydn, Mozart, and Beethoven were all active there. As the seat of the Holy Roman Empire (which included parts of present-day Austria, Germany, Italy, Hungary, Czech and Slovakia), it was a{{U}} (51) {{/U}}cultural and commercial center{{U}} (52) {{/U}}a cosmopolitan character. Its population of al most 250, 000 (in 1800) made Vienna the fourth largest city in Europe. All three{{U}} (53) {{/U}}masters were born elsewhere, but they were drawn to Vienna to study and to seek{{U}} (54) {{/U}}. In Vienna, Haydn and Mozart became close friends and influenced each other’s musical{{U}} (55) {{/U}}Beethoven traveled to Vienna at sixteen to play for Mozart; at twenty-two, he returned to study with Haydn. Aristocrats from all over the Empire spent the winter in Vienna, sometimes bringing their private{{U}} (56) {{/U}}. Music was an important part of court life, and a good orchestra was a{{U}} (57) {{/U}}of prestige. Many of the nobility were excellent musicians. Much music was heard in private concerts where aristocrats and wealthy commoners played{{U}} (58) {{/U}}professional musicians. Mozart and Beethoven often earned money by performing in these intimate concerts. The nobility{{U}} (59) {{/U}}hired servants who could{{U}} (60) {{/U}}as musicians. An advertisement in the Vienna Gazette of 1789{{U}} (61) {{/U}}: “Wanted, for a house of the gentry, a manservant who knows how to play the violin well.” In Vienna there was also outdoor music, light and popular in{{U}} (62) {{/U}}. Small street bands of wind and string players played at garden parties or under the windows of people{{U}} (63) {{/U}}to throw{{U}} (64) {{/U}}money. Haydn and Mozart wrote many outdoor entertainment{{U}} (65) {{/U}}, which they called divertimentos or serenades. Vienna’s great love of music and its enthusiastic demand for new works made it the chosen city of Haydn, Mozart and Beethoven.

单选题The car was completely written off and the driver seriously injured.

单选题What does "clear-air turbulence" probably mean? (Paragraph 1)

单选题Although technically we speak the same language, many British people feel the United Stated to be an Ualien/U culture.

单选题Driven to Distraction Joe Coyne slides into the driver's seat, starts up the car and heads to town. The empty stretch of interstate gives way to urban congestion, and Coyne hits the brakes as a pedestrian suddenly crosses the street in front of him. But even if he hadn't stopped in time, the woman would have been safe. She isn't real. Neither is the town. And Coyne isn't really driving. Coyne is demonstrating a computerized driving simulator that is helping researchers at Old Dominion University (ODU) examine how in vehicle guidance systems affect the person behind the wheel. The researchers want to know if such systems, which give audible or written directions, are too distracting—or whether any distractions are offset by the benefits drivers get from having help finding their way in unfamiliar locations. "We are looking at the performance and mental workload of drivers," said Caryl Baldwin, the assistant psychology professor leading the research, which involves measuring drivers' reaction time and brain activity as they respond to auditory and visual cues. The researchers just completed a study of the mental workload involved in driving through different kinds of environments and heavy, light traffic. Preliminary results show that as people "get into more challenging driving situations, they don't have any extra mental energy to respond to something else in the environment," Baldwin said. But the tradeoffs could be worth it, she said. The next step is to test different ways of giving drivers navigational information and how those methods change the drivers' mental workload. "Is it best if they see a picture... that shows their position, a map kind of display?" Baldwin said. "Is it best if they hear it?" Navigational systems now on the market give point by point directions that follow a prescribed route. "They're very unforgiving," Baldwin said. "If you miss a turn, they can almost seem to get angry." That style of directions also can be frustrating for people who prefer more general instructions. But such broad directions can confuse drivers who prefer route directions. Baldwin said. Perhaps manufacturers should allow drivers to choose the style of directions they want, or modify systems to present some information in a way that makes sense for people who prefer the survey style, she said. Interestingly, other research has shown that about 60 percent of men prefer the survey style, while 60 percent women prefer the route style, Baldwin said. This explains the classic little thing of why men don't like to stop and ask for directions and women do, Baldwin added.

单选题下面的短文有15处空白，请根据短文内容为每处空白确定1个最佳选项。 The Development of Rubber Here is the story of rubber. From the earliest time it was common knowledge {{U}}(51) {{/U}} the Peruvians that when a cut was made in the outside skin of a rubber tree, a white liquid {{U}}(52) {{/U}} milk came out, and that {{U}}(53) {{/U}} this a sticky (粘的) mass of rubber might be made. This rubber is soft when warm, so that it is possible to give it any {{U}}(54) {{/U}}. The Peruvians made the {{U}}(55) {{/U}} that it was very good for keeping out the wet. Then in the early 1800's, the Americans made use of it for the first time. First they made overshoes to {{U}}(56) {{/U}} their feet dry. Then came a certain Mr. Mackintosh, who made coats of cloth covered with natural rubber. From that day to this we have been coating cloth with rubber as Mr. Mackintosh {{U}}(57) {{/U}}, and our raincoats are still named after him. But these first rubber overshoes and raincoats were all soft and sticky in summer, and {{U}}(58) {{/U}} and inelastic (无弹性的) in the winter when it was col D. But the rubber we have today is soft and elastic (有弹性的), {{U}}(59) {{/U}} very strong m even in the warmest summer and the coldest winter. This was made {{U}}(60) {{/U}} by a man called Goodyear. After many {{U}}(61) {{/U}}, he found that nitric acid (硝酸) made the rubber much better, but it is not hard and strong enough. Then a strange thing took {{U}} (62) {{/U}}. A friend of his, Nicholas Hayward, had the idea in his sleep that rubber might be made hard and strong if mixed with sulfur (硫磺) and put in the sun. Goodyear put this idea {{U}}(63) {{/U}} the test, and saw that it did have more or less the desired effect though somewhat less than more. The only effect it had was on the outside of the rubber. It is common knowledge now that the {{U}}(64) {{/U}} to make rubber hard and strong is by heating it with sulfur. It took Goodyear four more years to find this metho D. When at last he did it, he had {{U}}(65) {{/U}} at all. Everything of the smallest value had been used to get money, even his sons' school-books.

单选题Do You Live in a Happy Country? Do you live in a happy country? Chances are strong that you do. Results of a recent study have shown that many people around the world are happier now than in the past. The study is called the World Values Survey. Researchers responsible for the study are based at the University of Michigan Institute for Social Research in the United States. The researchers gathered information from opinion studies done in more than ninety countries or territories. Those studies were completed between nineteen eighty-one and two thousand seven. University of Michigan political scientist Ronald Inglehart directed the World Values Survey. Mister Inglehart says the results surprised him. He said it is widely believed that it is nearly impossible for happiness levels for a whole country to improve. He said many earlier studies have suggested that happiness levels do not really change. Denmark was found to be the world's happiest country. Mister Inglehart notes that Denmark's health care is good and few Danes are hungry. Zimbabwe was rated as the least happy country. Zimbabweans have suffered from political and social unrest. Other nations in the top ten for happiness include Iceland, Switzerland, the Netherlands, Canada and Colombia. Colombia suffers from violence in some areas. But Mister Inglehart says Colombians share strong family, friendship and religious ties. He says those qualities are common in areas along the Caribbean Sea. And he says they help balance economic and political weakness. The researchers compared the most recent World Values Survey with information from a study completed in nineteen forty-six. Several areas showed rising happiness levels. They include India, Mexico, Northern Ireland, Puerto Rico and South Korea. Over the years, India's economy has grown. An improved financial situation is an important sign of happiness, the political scientist says. But living in a country that is becoming more democratic may be more important. So may acceptance of minorities. Mister Inglehart says the study shows a strong link between happiness and freedom to choose how life is lived. It shows that equality between men anti women is another reason. Mister Inglehart says Northern Ireland is doing well financially and moving toward sexual equality. He also says the area has the traditional bases of friendship, family ties and religion. Northern Ireland has suffered violence in the past. But he says most people there live a normal life today. Some places showed less happiness than in the past. They were Austria, Belgium, Britain and the former West Germany. However, Mister Inglehart says these areas were still in the top twenty-five percent for happiness last year. And, he says that rating still shows a good level of satisfaction.

单选题The term “composition” refers to the way the components of a drawing are {{U}}arranged{{/U}} by the artist.

单选题Why is the Native Language Learnt So Well? How does it happen that children learn their mother tongue so well? When we compare them with adults learning a foreign language, we often find this interesting fact. A little child without knowledge or experience often succeeds in a complete mastery of the language. A grown-up person with fully developed mental powers, in most cases, may end up with a faulty and inexact command. What accounts for this difference? Despite other explanations, the real answer in my opinion lies partly in the child himself, partly in the behaviour of the people around him. In the first place, the time of learning the mother tongue is the most favourable of all, namely, the first years of life. A child hears it spoken from morning till night and, what is more important, always in its genuine form, with the right pronunciation, right intonation, right use of words and right structure. He drinks in all the words and expressions which come to him in a fresh ever-bubbling spring. There is no resistance: there is perfect assimilation. Then the child has, as it were, private lessons all the year round, while an adult language-student had each week a limited number of hours which he generally shares with others. The child has another advantage: he hears the language in all possible situations, always accompanied by the right kind of gestures and facial expressions. Here there is nothing unnatural, such as is often found in language lessons in schools, when one talks about ice and snow in June or scorching heat in January. And what a child hears is generally what immediately interests him. Again and again, when his attempts at speech are successful, his desires are understood and fulfilled. Finally, though a child's "teachers" may not have been trained in language teaching, their relations with him are always close and personal. They take great pains to make their lessons easy.

单选题There is no risk to public health.

单选题Motoring Technology 1.2 million road deaths worldwide occur each year, plus a further 50 million injuries. To reduce car crash rate, much research now is focused on safety and new fuels though some electric vehicle and biofuel research aims at going faster. Travelling at speed has always been risky. One cutting edge area of research in motoring safety is the use of digital in-car assistants. They can ensure you don't miss crucial road signs or fall asleep. The use of artificial intelligence software allows these assistants to monitor your driving and makes sure your phone or radio doesn't distract you at a vital moment. Most crashes result from human and not mechanical faults. Some safety developments aim to improve your vision. Radar can spot obstacles in fog, while other technology "sees through" high-sided vehicles blocking your view. And improvements to seat belts, pedal controls and tyres are making driving smoother and safer. The color of a car has been found to be linked with safety, as have less surprisingly size and shape. And alternatives to fossil-fuel based petrol, such as plant oils, are a hot area of research. Fuel cells based on hydrogen burn cleanly, and are the subject of a serious research effort. But whatever is in the fuel tank, you don't want a thief in the driving seat and there have been many innovations, some using satellite tracking and remote communications, to fight against car theft. These communication systems can also come into play if you crash, automatically calling for help. Accidents cause many traffic jams, but there are more subtle interplays between vehicles that can cause jams even on a clear but busy road. Such jams can be analyzed using statistical tools. Robotic drivers could be programmed to make traffic flow smoothly and will perhaps one day be everyone's personal chauffeur, but their latest efforts suggest that won't be soon.

单选题The father was unwilling to give his son the keys to his car.

单选题Unless checked, rabbits can generate rapidly when conditions are in their favor. A. injured B. controlled C. marked D. examined

单选题A salesman’s {{U}}cardinal{{/U}} rule is to satisfy customers.

单选题The most famous Shoshone Indian was Sacagawea—the woman who accompanied Lewis and Clark on their exploration of the upper Missouri River.

单选题A lot of people could fall ill after drinking contaminated water.