单选题"Life Form Found" on Saturn's Titan Scientists say they have discovered hints of alien life on the Saturn's moon. The discovery of a sort of life was announced after researchers at the US space agency, NASA, analyzed data from spacecraft Cassini, which pointed to the existence of methane-based form of life on Saturn's biggest moon. Scientists have reportedly discovered clues showing primitive alien beings are "breathing" in Titan's dense atmosphere filled with hydrogen. They argue that hydrogen gets absorbed before hitting Titan's planet-like surface covered with methane lakes and rivers. This, they say, points to the existence of some "bugs" consuming the hydrogen at the surface of the moon less than half the size of the Earth. "We suggested hydrogen consumption because it's the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth," says NASA scientist Chris McKay. "If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth. " To date, scientists have not yet detected this form of life anywhere, though there are liq-uid-water-based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin (minus 290 degrees Farenheit), a methane-based organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan's surface and much too cold to support life as we know it. Scientists had expected the Sun's interactions with chemicals in the atmosphere to produce a coating of acetylene on Titan's surface. But Cassini detected no acetylene on the surface. The absence of detectable acetylene on the Titan's surface can very well have a non-bio-logical explanation, said Mark Allen, a principal investigator of the NASA Titan team. "Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed," Alien said. "We have a lot of work to do to rule out possible non-biological explanations. It is more likely that a chemical process, without biology, can explain these results. /

单选题Since about 1970, new research has helped brain scientists understands these problems better. Scientists now know there are many different kinds of learning disabilities and that they are caused by many different things. There is no longer any question that all learning disabilities result from differences in the way the brain is organized. You can' t look at a child and tell if he or she has a learning disability. There is no outward sign of the disorder. So some researchers began looking at the brain itself to learn what might be wrong. In one study, researchers examined the brain of a learning disabled person who had died in an accident. They found two unusual things. One involved cells in the left side of the brain, which control language. These cells normally are white. In the learning disabled person, however, these ceils were gray. The researchers also found that many of the nerve ceils were not in a line the way they should have been. The nerve cells were mixed together. The study was carried out under the guidance of Norman Geschwind, an early expert on learning disabilities. Doctor Geschwind proposed that learning disabilities mainly resultes from problems in the left side of the brain. He believed this side of the brain failed to develop normally. Probably, he said, nerve cells there didn't connect as they should. So the brain was like an electrical device in which the wires were crossed. Other researchers didn't examine brain tissue. Instead, they measured the brain's electrical activity and made a map of the electrical signals. Frank Dully experimented with this technique at Children's Hospital Medical Center in Boston. Dr. Duffy found large differences in the brain activity of normal children and those with reading problems. The differences appeared throughout the brain. Dr. Dully said his research is evidence that reading disabilities involve damage to a wide area of the brain, not just the left side.

单选题The nursery is bright and cheerful .

单选题The child"s abnormal behavior puzzled the doctor.

单选题As both a religion and a social force, Puritanism has made a widespread influence in the United States.

单选题The question is ______ my understanding and I am completely at a loss.A. beyondB. besideC. exceedD. over

单选题I wanted to ask her out but was scared that she might refuse.

单选题It can be learned about form the paragraph that_____.

单选题The dragon-boating day is ______ the death of Qu. Yuan, the great poet in china.A. in accordance withB. in terms ofC. in favor ofD. in honor of

单选题Twins do not always display a noticeable {{U}}likeness{{/U}}.

单选题Her {{U}}specialty{{/U}} is heart surgery.

单选题About one quarter of the workers in the country are employed in factories.

单选题The best olive oil is obtained from olives that are {{U}}harvested{{/U}} just after they ripen and before they turn black.

单选题We have never seen such {{U}}gorgeous {{/U}} hills.

单选题I don't know what makes Christina so {{U}}attractive{{/U}} to young men.

单选题{{B}}第三篇{{/B}} {{B}} Changes in the American Family{{/B}} How much change has really occurred in the American family and what are the implications of these changes? First, the household size has changed greatly since 1790. From 1790 to 1978 the mean family size was cut in half from 5.79 persons to 2.81 persons. In 1790 almost 63 percent of all persons lived in the households of five or more people. By 1978 the size accounted for a little over 14 percent of all households. By the end of the 19th century a majority of Americans were living in urban areas, and the family was very much influenced By the rapid development of industrialization. With the arrival of immigrants, the urban population was increasingly heterogeneous(由不同成分组成的). This challenges the exclusiveness of any single family pattern. In the 20th century, the ideal American family consisted of a husband and wife living with dependent children. They lived in a household of their own provided for by the husband's earnings. The wife was responsible for emotional maintenance of the marriage and for raising the children and running the household. The major change in the family in this century has been due to married women entering the work force. This, at least for periods of time, has taken the woman out of her full-time involvement in the home. Of all husband and wife families about 40% have both in the work force at any given time. In the past the identity of the individual was submerged in the family. In general, reputation in the community came from the family. Today, however, whatever individuals achieve is usually assessed on its own merit, and family has little relevance. Individuals make it or don't make it essentially on their own. A sociologist describes another way in which the American family has changed. Today, in the Western world, the major burdens that are a part of the family system are emotional ones. But in the 19th century the family was much more involved with economic needs and tasks; family and relatives were valued for providing assistance during crisis.

单选题第二篇 Can Buildings Be Designed to Resist Terrorist Attack In the aftermath of the terrorist attack on the World Trade Center, structural engineers are trying hard to solve a question that a month ago would have been completely unthinkable: Can building be designed to withstand catastrophic blasts inflicted by terrorists? Ten days after the terrorist attacks on the twin towers, structural engineers from the University at Buffalo and the Multidisciplinary Center for Earthquake Engineering Research (MCEER) headquartered at UB traveled to ground zero as part of a project funded by the National Science Foundation. Visiting the site as part of an MCEER reconnaissance visit, they spent two days beginning the task of formulating ideas about how to design such structures and searching for clues on how to do so in buildings that were damaged, but still are standing. "Our objective in visiting ground zero was to go and look at the buildings surrounding the World Trade Center, those buildings that are still standing, but that sustained damage," said M. Bruneau, Ph.D. "Our immediate hope is that we can develop a better understanding as to why those buildings remain standing, while our long-term goal is to see whether earthquake engineering technologies can be married to existing technologies to achieve enhanced performance of buildings in the event of terrorist attacks." he added. Photographs taken by the investigators demonstrate in startling detail the monumental damage inflicted on the World Trade Center towers and buildings in the vicinity. One building a block away from the towers remains standing, but was badly damaged. "This building is many meters away from the World Trade Center and yet we see a column there that used to be part of that building", explained A. Whittaker, Ph. D. "The column became a missile that shot across the road, through the window and through the floor." The visit to the area also revealed some surprises, according to the engineers. For example, the floor framing systems in one of the adjacent buildings was quite rugged, allowing floors that were pierced by tons of falling debris to remain intact. "Highly redundant ductile framing systems may provide a simple, but robust strategy for blast resistance." he added. Other strategies may include providing alternate paths for gravity loads in the event that a load-bearing column fails. "We also need a better understanding of the mechanism of collapse", said A. Whittaker. "We need to find out what causes a building to collapse and bow you can predict it." A. Reinhorn, Ph.D. noted that "earthquake shaking has led to the collapse of many buildings in the past. It induces dynamic response and extremely high stresses and deformations in structural components. Solutions developed for earthquake-resistant design may be directly applicable to blast engineering and terrorist-resistant design. Part of our mission now at UB is to transfer these solutions and to develop new ones where none exist at present."

单选题It"s prudent to start any exercise program gradually at first.

单选题Sports Star Yao Ming If Yao Ming is not the biggest sports star in the world, he is almost certainly the tallest. At 2.26m, he is the tallest player in the National Basketball Association (NBA) and holds the record as the most towering Olympian ever to compete in the Games. But what really stands out about the giant center is his celebrity (名气). Few, if any, Chinese athletes are as well-known as Yao around the world. People across the globe are fascinated with Yao, not only for his basketball prowess (杰出的才能) but also for being a symbol of international commerce. When Yao joined the Houston Rockets as the No. 1 pick in the 2002 NBA draft (选拔), he was the first international player ever to be selected first. His assets on the court are clear enough—no NBA player of his size has ever possessed his mobility, so he is a handful (难对付的人) for opponents on either end of the court. But what makes Yao invaluable to the Rockets organization is his role as a global citizen and as a bridge to millions of potential basketball fans in China. When it was announced in February that Yao would miss the rest of the NBA season and possibly the Olympics with a stress fracture (骨折) in his left foot, a collective shudder (震动) spread across China. After considerable debate and discussion, Yao opted to get his foot surgically treated in an operation that placed several tiny screws across the bone, to offer his overburdened foot more support. The surgery was a success, and though the estimated four-month recovery period will leave him little time to prepare with Team China, Yao has vowed to be ready for the Beijing Olympics. Yao wrapped up a 10-day trip to China, where he underwent a series of traditional Chinese medicine (TCM) treatments, hoping to accelerate his recovery process. Western experts are generally skeptical of TCM"s benefits, although new research from the University of Rochester suggests that a certain compound derived from shellfish may indeed stimulate bone repair. "There is no reason to dismiss TCM," Yao told a press conference in Beijing. "It"s been used in our country for thousands of years. I don"t think that it"s short on science."

单选题Her life is becoming more diverse .