单选题 Cell Phone Lets Your Secret Out Your cell phone holds secrets about you. Besides the names and {{U}} {{U}} 1 {{/U}} {{/U}}that you've programmed into it, traces of your DNA linger on the device, according to a new study. DNA is genetic material that {{U}} {{U}} 2 {{/U}} {{/U}}in every cell. Like your fingerprint, your DNA is unique to you—{{U}} {{U}} 3 {{/U}} {{/U}}you have an identical twin. Scientists today routinely analyze DNA in blood, saliva, or hair left {{U}} {{U}} 4 {{/U}} {{/U}}at the scene of a crime. The results often help detectives identify {{U}} {{U}} 5 {{/U}} {{/U}}and their victims. Your cell phone can reveal more about you {{U}} {{U}} 6 {{/U}} {{/U}}you might think. Meghan J. McFadden, a scientist at McMaster University in Hamilton, Ontario, heard about a crime in which the suspect bled onto a cell phone and later dropped the {{U}} {{U}} 7 {{/U}} {{/U}}. This made her wonder whether traces of DNA lingered on cell phones-even when no blood was involved. {{U}} {{U}} 8 {{/U}} {{/U}}she and colleague Margaret Wallace of the City University of New York analyzed the flip open phones of 10 volunteers. They used swabs to collect {{U}} {{U}} 9 {{/U}} {{/U}}traces of the users from two parts of the phone: the outside, where the user holds it, and the {{U}} {{U}} 10 {{/U}} {{/U}}, which is placed at the user's ear. The scientists scrubbed the phones using a solution made mostly {{U}} {{U}} 11 {{/U}} {{/U}}alcohol. The aim of washing was to remove all detectable traces of DNA. The owners got their phones {{U}} {{U}} 12 {{/U}} {{/U}}for another week. Then the researchers collected the phones and repeated the swabbing of each phone once more. The scientists discovered DNA that {{U}} {{U}} 13 {{/U}} {{/U}}to the phone's speaker on each of the phones. Better samples were collected from the outside of each phone, but those swabs also picked up DNA that belonged to other people who had apparently also handled the phone. {{U}} {{U}} 14 {{/U}} {{/U}}, DNA showed up even in swabs that were taken immediately after the phones were scrubbed. That suggests that washing won't remove all traces of evidence from a criminal's device. So cell phones can now be added to the {{U}} {{U}} 15 {{/U}} {{/U}}of clues that can clinch a crime scene investigation.

单选题 阅读下面这篇短文，短文后列出7个句子，请根据短文的内容对每个句子做出判断。 {{B}}Hierarchy{{/B}} Culture is the sum total of all the traditions, customs, beliefs, and ways of life of a given group of human beings. In this sense every group has a culture however savage, undeveloped, or uncivilized it may seem to us. To the professional anthropologist, there is no intrinsic superiority of one culture over another, just as to the professional linguist there is no intrinsic hierarchy among languages. People once thought of the languages of backward groups as savage, undeveloped forms of speech, consisting largely of grunts (呼噜声) and groans (呻吟). While it is possible that language in general began as a series of grunts and groans, it is a fact established by the study of "backward" languages that no spoken tongue answers that description today. Most languages of uncivilized groups are, by our most severe standards, extremely complex, delicate, and ingenious pieces of machinery for the transfer of ideas. They fall behind our Western languages not in their sound patterns or grammatical structures, which usually are fully adequate for all language needs, but only in their vocabularies, which reflect the objects and activities known to their speakers. Even in this department, however, two things are to be noted: (1) All languages seem to possess the machinery for vocabulary expansion, either by putting together words already in existence or by borrowing them from other languages and adapting them to their own system. (2)The objects and activities requiring names and distinctions in "backward" languages; while different form ours, are often surprisingly numerous and complicated. A Western language distinguishes merely between two degrees of remoteness ("this" and "that"); some languages of the American Indians distinguish between what is close to the speaker, or to the person addressed, or removed from both, or out of sight, or in the past, or in the future. This study of language, in turn, casts a new light upon the claim of the anthropologists that all cultures are to be viewed independently, and without ideas of rank or hierarchy.

单选题Climate Change Poses Major Risks for Unprepared Cities A new examination of urban policies has been 1 recently by Patricia Romero Lankao. She is a sociologist specializing in climate change and 2 development. She warns that many of the world"s fast-growing urban areas, especially in developing countries, will likely suffer from the impacts of changing climate. Her work also concludes that most cities are failing to 3 emissions of carbon dioxide and other greenhouse 4 . These gases are known to affect the atmosphere. "Climate change is a deeply local issue and poses profound threats to the growing cities of the world." says Romero Lankao. "But few cities are developing effective strategies to 5 their residents." Cities are 6 sources of greenhouse gases. And urban populations are likely to be among those most severely affected by future climate change. Lankao"s findings highlight ways in which city residents are particularly vulnerable, and suggest policy interventions that could offer immediate and longer-term 7 . The locations and dense construction patterns of cities often place their populations at greater risk for natural disasters. Potential 8 associated with climate include storm surges and prolonged hot weather. Storm surges can flood coastal areas and prolonged hot weather can heat 9 paved cities more than surrounding areas. The impacts of such natural events can be more serious in an urban environment. For example, a prolonged heat wave can increase existing levels of air pollution, causing widespread health problems. Poorer neighborhoods that may 10 facilities such as drinking water or a dependable network of roads, are especially vulnerable to natural disasters. Many residents in poorer countries live in substandard housing 11 access to reliable drinking water, roads and basic services. Local governments, 12 , should take measures to protect their residents. "Unfortunately, they tend to move towards rhetoric 13 meaningful responses," Romero Lankao writes. They don"t impose construction standards that could reduce heating and air conditioning needs. They don"t emphasize mass transit and reduce 14 use. In fact, many local governments are taking a hands-off approach. Thus, she urges them to Change their 15 policies and take strong steps to prevent the harmful effects of climate change on cities.

单选题A Country's Standard of Living The "standard of living" of any country means the average person's share of the goods and services the country produces. A country's standard of living, therefore (51) first on its capacity to produce wealth. "Wealth" in this (52) is not money, for we do not live on money but on things that money can buy: "goods" such as food and clothing, and "services" such as transport and entertainment. A country's capacity to (53) wealth depends upon many factors, most of (54) have an effect on one another. Wealth depends (55) a great extent upon a country's natural resources. Some regions of the world are well supplied with coal and minerals, and have fertile soil and a favorable climate; other regions (56) none of them. Next to natural resources comes the ability to (57) them to use. China is perhaps as rich as the USA in natural resources, but suffered for many years (58) civil and external wars and for this and other (59) was unable to develop her resources. Sound and stable political conditions, and (60) from foreign invasions, enable a country to develop its natural resources peacefully and steadily, and to produce more (61) than another country equally well favored by nature but less well ordered. A country's standard of living does not only depend upon the wealth that is produced and (62) within its own borders, but also upon what is directly produced through international trade, for example, Britain's wealth in foodstuffs and other agricultural (63) would be much less if she had to depend only on those grown at home. Trade makes it possible for her surplus (过剩的) manufactured goods to be traded abroad for the agricultural products (64) would otherwise be lacking. A country's wealth is, therefore, much influenced by its manufacturing capacity (65) that other countries can be found ready to accept its manufactures.

单选题There are as many wise managers as there are stupid ones.

单选题On the table was a vase filled with artificial flowers.

单选题According to the passage, which of the following is true of the small businesses in the US?

单选题The policeman wrote down all the particulars of the accident. A. secrets B. details C. benefits D. words

单选题"Salty" Rice Plant Boosts Harvests British scientists are breeding a new generation of rice plants that will be able to grow in soil containing salt water. Their work may enable abandoned farms to become productive once more. Tim Flowers and Tony Yeo, from Sussex University's School of Biological Sciences, have spent several years researching how crops, such as rice, could be made to grow in water that has become salty. The pair have recently begun a three-year programme, funded by the Biotechnology and Biological Sciences Research Council, to establish which genes enable some plants to survive salty conditions. The aim is to breed this capability into crops, starting with rice. It is estimated that each year more than 100 hectares(公顷) of agricultural land are lost because salt gets into the soil and stunts(妨碍生长) plants. The problem is caused by several factors. In the tropics, mangroves(红树林) that create swamps(沼泽) and traditionally formed barriers to sea water have been cut down. In the Mediterranean, a series of droughts have caused the water table to drop, allowing sea water to seep(渗透) in. In Latin America, irrigation often causes problems when water is evaporated(蒸发) by the heat, leaving salt deposits behind. Excess salt then enters the plants and prevents them functioning normally. Heavy concentrations of minerals in the plants stop them drawing up the water they need to survive. To overcome these problems, Flowers and Yeo decided to breed rice plants that take in very little slat and store what they do absorb in cells that do not affect the plants' growth. They have started to breed these characteristics into a new rice crop, but it will take about eight harvests before the resuiting seeds are ready to be considered for commercial use. Once the characteristics for surviving salty soil are known, Flowers and Yeo will try to breed the appropriate genes into all manners of crops and plants. Land that has been abandoned to nature will then be able to bloom again, providing much needed food in the poorer countries of the world.

单选题They voted to abolish the office of second vice-president.

单选题In recent years, there has been an increased awareness of the importance of protecting the environment. The three Rs to keep in mind for a cleaner environment are: reduce, reuse, and recycle. First, reduce how much you use. It means shopping with the environment in mind. Consider the environmental impact of each product before you buy it. Make a list of what you need before you go shopping; this will reduce impulse buying. Buy in bulk - its cheaper and eliminates small containers and excess packaging. Besides, bulk merchandise may be shared with friends or neighbors. You should also avoid buying things that can't by recycled. A shopping list can helpA. find cheaper items.B. reduce impulsive buying.C. eliminate small containers.D. avoid excess packagin

单选题I rarely wear a raincoat because I spend most of my time in a car A. normally B. seldom C. frequently D. usually

单选题The Spanish, French, Dutch, and English all vied for North American territory.

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 (寿命) of mice by 18 per cent by blocking the rodent's (啮齿动物) increase of fat in specific cells. This suggests that thinness-and not necessarily diet-promotes long life in "calorie (热量卡) 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 per cent less body fat than normal control mice, despite the fact that they ate 55 per cent 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Unlike gases, liquids are difficult to compress because there is practically no free space between molecules.A. In contrast toB. Similar toC. More toD. Just as

单选题The normal price of a ticket for an adult is $ 230.A. ordinaryB. properC. fairD. medium

单选题You startled me when you shouted.

单选题She {{U}}exhibited{{/U}} great powers of endurance during the climb. A. play B. send C. show D. tell

单选题From the beginning, water has furnished mail with a source of food and a highway to travel upon. The first civilizations arose where water was a dominant element in the environment, a challenge to man's ingenuity. The Egyptians invented the 365 - day calendar in response to the Nile's annual flooding. The Babylonians, who were among the most famous law -makers in ancient times, invented laws regulating water usage. Water inspired the Chinese to built a 1,000 - mile canal - a complex system, which, after nearly 2,500 years, remains still practically in use and still commands the astonishment of engineers. But the ancients never found complete solutions to their water problems. The Yellow River is also known as" China's Sorrow" ;it is so unpredictable and dangerous that in a single flood it has caused a million deaths. Floods slowed the great civilization of the Indus River Valley, and inadequate drainage ruined much of its land. Today water dominates man as it always has done. Its presence continues to govern the location of his homes and cities; its violent variability can kill man or his herds or his crops; its routes links him to his fellows; its immense value may add to already dangerous political conflicts. There are many examples of this in our own time. Who of the following were among the most famous law makers?A. The ancient Chinese.B. The ancient Egyptians.C. The ancient Babylonians.D. The ancient Indians.

单选题While we don"t agree, we continue to be friends.