单选题About eight million school-age children are home alone after school. These are the hours when the number of violent crimes peaks and when youths are most likely to experiment with alcohol, tobacco, and drugs. Many older children take care of themselves after school for an hour or two until a parent comes home, and research suggests that some of these children are more at risk of poor grades and risky behaviors. Studies have been done to find out what helps to reduce these kinds of risky behaviors among youths. One study of Chicago neighborhoods showed that after-school programs resulted in less violence even in poor neighborhoods. After-school programs can help to reduce crime and violence because they offer activities to children and youths during their out-of-school time. In addition to helping youths make use of after-school hours, after-school programs provide teens with opportunities to develop caring relationships with adults. Studies have found that high-quality relationships with parents and other adults, as well as good use of time, are very important for healthy development in youth. After-school programs can also be used for teens who hang out at friends" houses and play basketball when a parent or other responsible adult is at home. The programs can also be helpful for formal after-school activities, including "drop-in" programs that are provided by organizations. Despite the benefits of after-school programs, there are many reasons why some parents do not use them. Programs may be too expensive, of poor quality, or hard to join. Some older children and young teens may refuse to attend programs that seem like they are just child care. Parents may feel uncertain about how much freedom is proper for children and youths who are beyond the traditional child care years. However, research supports the effectiveness of these programs in protecting middle school and high school youths from risk and harm.

单选题Sharks Perform a Service for Earth's Waters It is hard to get people to think of sharks as anything but a deadly enemy. They are thought to (51) people frequently. But these fish perform a (52) service for earth's waters and for human beings. Yet business and sport fishing are threatening their (53) . Some sharks are at risk of disappearing from (54) . Warm weather may influence both fish and shark activity. Many fish swim near coastal areas (55) their warm waters. Experts say sharks may follow the fish into the same areas, (56) people also swim. In fact, most sharks do not purposely charge at or bite humans. They are thought to mistake a person (57) a sea animal, such as a seal or sea lion. That is why people should not swim in the ocean when the sun goes down or comes up. Those are the (58) when sharks are looking for food. Experts also say that bright colors and shiny jewelry may cause sharks to attack. A shark has an extremely good sense of smell. It can find small amounts of substances in water, such as blood, body liquids and (59) produced by animals. These powerful (60) help sharks fred their food. Sharks eat fish, any (61) sharks, and plants that live in the ocean. Medical researchers want to learn more about the shark's body defense, and immune (62) against disease. Researchers know that sharks (63) quickly from injuries. They study the shark in hopes of finding a way to fight human disease. Sharks are important for the world's (64) . They eat injured and diseased fish. Their hunting activities mean that the numbers of other fish in ocean waters do not become too (65) . This protects the plants and other forms of life that exist in the oceans.

单选题These factors interact {{U}}intimately{{/U}} and cannot be separated. A. tensely B. nearly C. carefully D. closely

单选题A beautiful woman attended to me in that store yesterday.A. waited onB. talked toC. spoke toD. stayed with

单选题We were astonished to hear that their football team had won the champion.

单选题Cold air causes the arteries around the heart to {{U}}constrict{{/U}}.

单选题Warmer Climate Will Bake Tropical Bugs Global warming could cook tropical insects, with unpredictable knock-on effects, say researchers who warn that rising temperatures also 1 tropical frogs and lizards (蜥蜴). Temperatures are 2 to increase much faster in temperate (温和的)and polar (极地 的) regions than in the tropics. But no one had looked at how warming would affect insects and other cold-blooded animals 3 had evolved in tropical regions with little temperature variation. Curtis Deutsch at the University of California at Los Angeles and colleagues analysed data 4 insect survival and reproduction for 38 species in different ecosystems (生态系统), and then estimated how these values would 5 with predictions of climate change for the 21st century. The team found that the reproductive 6 of tropical insects tends to peak very close to the temperatures where they normally live, but 7 sharply at higher temperatures. This means that cranking up (提高) the heat only a small amount can exert a heavy toll, leaving insects unable to reproduce 8 enough to keep up their numbers. Temperate insects reproduce well over a broader range, and do not live as 9 to their thermal (热的) limit, so they can reproduce successfully when their climate warms more than in the tropics. "Tropical insects do very well in a narrow band of temperatures, but move them above that 10 and they die," says team member Josh Tewksbury of the University of Washington in Seattle. The heart of the 11 is temperature tolerance. Temperate-zone insects have evolved to survive the much broader temperature range of seasonal climates than have their tropical relatives. The 12 appears worse for animals that live in hot stable climate of the lower levels of tropical forests. Lizards in clear areas can find shade to cool down, but those living in the forest are already in the 13 , and there"s not much they can do to get cooler, Deutsch says. Too few tropical insects have been studied so far to 14 if any particular group will be particularly hard-hit, says Tewksbury. Insects play important 15 in forest ecology (生态学). The team are now starting to evaluate how temperature affects ecological interactions of insects with other species, including crops such as African corn.

单选题These are defensive behavior patterns which derive from our fears.

单选题As they move, glaciers push piles of rocks {{U}}ahead of{{/U}} them.

单选题Have you talked to her lately ?

单选题I had some difficulty in carrying out the plan. A. making B. keeping C. changing D. implementing

单选题 下面的短文后列出了7个句子，请根据短文的内容对每个句子做出判断；如果该句提的是正确信息，请选择A，如果该句提的是错误信息，请选择B；如果该句的信息文中没有提及，请选择C。 Sonic Device The other day, Dr. Robert Smith, who is blind, took a remarkable stroll through the campus of the University of California at Santa Barbara. As Dr. Smith walked along the campus, places and impediments (障碍物) in his path seemed to call out their names to him, "library here, library here", "bench here, bench here". Dr. Smith was testing a prototype(样机) navigation system for the blind that announced the surrounding objects through stereo headphones that were mounted to a computer in his back-pack (背包),creating virtual reality landscape(仿真景象). The information came not from some miniature radar but from the signals broadcast by the military's network of global positioning satellites(全球定位卫星). One day, its developers hope, miniaturized (小型化)versions of this navigation device, which now weighs 28 pounds, will help the blind navigate unfamiliar neighborhoods. "With this system you do not need to know a thing in advance about where you are going," said Dr. Roberta Klatzky, a psychologist at Carnegie Mellon University who is working with Dr. Smith to develop the navigating device. Dr. Michael Oberdor of the National Eye Institute said, "A blind person could walk down the street and know not just that he was at 80th and Broadway, but what stores are around, and that Zabar's delicatessen(熟食店) was up ahead. This navigation system tells you not just where there are obstacles, but your overall location geographically. " It lets blind users construct a mental map of new surroundings and learn their way around. The navigation system uses signals from a computerized map to create a "virtual acoustic display(仿真声音显示)" This is a talking map in which large objects seem to announce themselves in the headphones with the precise timing and loudness that would be the case if the objects were actually making a sound. This allows the blind person to sense immediately his or her distance or direction, and use that information for guidance. While no one knows whether it is because blind people tend to develop a sharper sense of hearing. Those who have tried the system say that they quickly adapt to locating an object through the sounds. "One of the crucial features of this system is that it takes advantage of sensory psychophysics(感官心理物理学)-how the brain interprets signals from outside to make a map of your surroundings so you can navigate, " Dr. Oberdor said.

单选题Will Quality Eat up the U. S. Lead in Software? If U. S. software companies don"t pay more attention to quality, they could kiss their business good-bye. Both India and Brazil are developing a world-class software industry. Their weapon is quality and one of their jobs is to attract the top U. S. quality specialists whose voices are not listened to in their country. Already, of the world"s 12 software houses that have earned the highest rating in the world, seven are in India. That"s because they have used new methodologies rejected by American software specialists. For example, for decades, quality specialists, W. Edwards Deming and J. M. Juran had urged U. S. software companies to change their attitudes to quality. But their quality call mainly fell on deaf ears in the U. S—but not in Japan. By the 1970s and 1980s, Japan was grabbing market share with better, cheaper products. They used Deming"s and Juran"s ideas to bring down the cost of good quality to as little as 5% of total production costs. In U. S. factories, the cost of quality then was 10 times as high: 50%. In software, it still is. Watts S. Humphrey spent 27 years at IBM heading up software production and then quality assurance. But his advice was seldom paid attention to. He retired from IBM in 1986. In 1987, he worked out a system for assessing and improving software quality. It has proved its value time and again. For example, in 1990 the cost of quality at Raytheon Electronics Systems was almost 60% of total software production costs. It tells to 15% in 1996 and has since further dropped to below 10%. Like Deming and Juran, Humphrey seems to be winning more praises overseas than at home. The Indian government and several companies have just founded the Watts Humphrey Software Quality Institute at the Software Technology Park in Chennai, India. Let"s hope that U. S. lead in software will not be eaten up by its quality problems.

单选题The Victorian speaker was noted for his {{U}}manual{{/U}} gestures.

单选题The high-speed trains can have a major impact on travel preferences. A. force B. influence C. surprise D. power

单选题She overcame her {{U}}initial{{/U}} shyness and really enjoyed the evening.

单选题 Download Knowledge Directly to Your Brain For the first time, researchers have been able to hack into the process of learning in the brain, using induced brain patterns to create a learned behavior. It's not quite as advanced as an instant kung-fu download, and it's not as sleek as cognitive inception, but it's still an important finding that could lead to new teaching and rehabilitation techniques. Future therapies could decode the brain activity patterns of an athlete or a musician, and use them as a benchmark for teaching another person a new activity, according to the researchers. Scientists from Boston University and ATR Computational Neuroscience Laboratories in Kyoto used functional magnetic resonance imaging, or fMRI, to study the learning process. They were examining the adult brain's aptitude for visual perceptual learning, or VPL, in which repetitive training improves a person's performance on a particular task. Whether adults can do this as well as young people has been an ongoing debate in neuroscience. Led by BU neuroscientist Takeo Watanabe, researchers used a method called decoded fMRI neurofeedback to stimulate the visual cortex. First they showed participants circles at different orientations. Then they used fMRI to watch the participants' brain activity. The researchers were then able to train the participants to recreate this visual cortex activity. The volunteers were again placed in MRI machines and asked to visualize shapes of certain colors. The participants were asked to "somehow regulate activity in the posterior part of the brain" to make a solid green disc as large as they could. They were told they would get a paid bonus proportional to the size of this disc, but they weren't told anything about what the disc meant. The researchers watched the participants' brain activity and monitored the activation patterns in their visual cortices. "Participants can be trained to control the overall mean activation of an entire brain region, " the study authors write, "or the activation in one region relative to that in another region. " This worked even when test subjects were not aware of what they were learning, the researchers said. "The most surprising thing in this study is that mere inductions of neural activation patterns corresponding to a specific visual feature led to visual performance improvement on the visual feature, without presenting the feature or subjects' awareness of what was to be learned, " Watanabe said in a statement. Watanabe and colleagues said this method can be a powerful tool. "It can 'incept' a person to acquire new learning, skills, or memory, or possibly to restore skills or knowledge that has been damaged through accident, disease, or aging, without a person's awareness of what is learned or memorized, " they Write.

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. Traveling at speed has always been dangerous. One advanced area of research in motoring safety is the use of digital in-car assistants. They can ensure you don't miss important road signs or fall asleep. 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" big vehicles blocking your view. And improvements to seat belts, pedal (脚踏)controls and tires 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. But whatever is in the fuel tank, you don't want a thief in the driving seat and there have been many innovations(创新). Satellite tracking and remote communications 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(司机) , but their latest efforts suggest that won't be soon.

单选题阅读下面的短文，文中有15处空白，每处空白给出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。 A satisfactory psychological theory must allow us to predict behavior. For instance, a satisfactory theory of hunger will allow us to predict when people will eat and not eat. A broadly satisfying, {{U}} (51) {{/U}}theory should have a wide range of applicability. A broad theory of hunger might apply {{U}} (52) {{/U}}human beings and lower animals, to normal weight and overweight people, and to people who have{{U}} (53) {{/U}}of food for differing lengths of time. If our{{U}} (54) {{/U}}cannot be adequately explained by or predicted from a given theory, we should consider revising or replacing that theory. In psychology many theories have been found to be{{U}} (55) {{/U}}of explaining or predicting new observations. As a result they have been revised{{U}} (56) {{/U}}.For example, the theory that hunger results from stomach contractions may be{{U}} (57) {{/U}}correct for normal weight individuals, but it is inadequate as an{{U}} (58) {{/U}}for feelings of hunger among the overweight.{{U}} (59) {{/U}}theories also focus on biological variables, such as fat cells and brain {{U}} (60) {{/U}}, and psychological variables such as the presence of other people who are eating and the time of day. The{{U}} (61) {{/U}}of controlling behavior in psychology is highly{{U}} (62) {{/U}}. Some people erroneously think that psychologists seek ways to make people do their bidding—like puppets dangling on strings. This is not so. Instead, psychologists help{{U}} (63) {{/U}}change their behavior for their own benefit. Psychologists are{{U}} (64) {{/U}}to belief in the dignity of human beings, and human dignity demands that people be free to make their own decisions and choose their own behavior. Psychologists are learning more all the time about the{{U}} (65) {{/U}}influences on human behavior, but they apply this knowledge only upon request and in ways they believe will be helpful to an individual or an institution.

单选题The doctors did not reveal the truth to him.