单选题The advantage of the new handgrip is that

单选题" The utilities are more interested in protecting their stranglehold on the power grid and preserving their century-old business model than they are producing clean electricity," says Jim Harvey, who heads up the Joshua Tree, Calif. — based Alliance for Responsible Energy Policy, an advocacy group that's staunchly opposed to utility-generated solar power. Harvey actually believes that the country's entire renewable portfolio can be achieved through rooftop solar alone. That may be possible from a sheer megawatts perspective, but from a practical standpoint, it's way over— ambitious. With no centralized source, how do you run traffic or street lights? What if it rains for a week? We still don't have foolproof means to store solar power, so for how, distributed generation needs the grid as a backup. What does the author think of Harvey's idea of achieving the country's entire renewable portfolio through rooftop solar alone?A. It is possible.B. It is not practical.C. It is out of question.D. It takes time to se

单选题The last few weeks have been enjoyable. A. close B. near C. past D. several

单选题Marvelous Metamaterials Invisibility cloaks would have remained impossible, forever locked in science fiction, had it not been for the development of metamaterials. In Greek, "meta" means beyond, and metamaterials can do things beyond what we see in the natural world—like shuffle light waves around an object, and then bring them back together. If scientists ever man-age to build a full-fledged invisibility cloak, it will probably be made of metamaterials. "We are creating materials that don"t exist in nature, and that have a physical phenomenon that doesn"t exist in nature," says engineer Dentcho Genov. "That is the most exciting thing." Genov designs and builds metamaterials—such as those used in cloaking, at Louisiana Tech University in Ruston, Louisiana. An invisibility cloak will probably not be the first major accomplishment to come from the field of metamaterials. Other applications are just as exciting. In many labs, for example, scientists are working on building a hyperlens. A lens is a device, usually made of glass, that can change the direction of light waves. Lenses are used in microscopes and cameras to focus light, thus allowing a researcher to see small things or a photographer to capture image of things that are far away. A hyperlens, however, would be made of metamaterials. And since metamaterials can do things with light that ordinary materials can"t, the hyperlens would be a powerful tool. A hyperlens would allow researchers to see things at the smallest scale imaginable as small as the wavelength of visible light. Genov points out that the science of metamaterials is driven by the imagination. If someone can think of an idea for a new behavior for light, then the engineers can find a way to design a device using metamaterials. "We need people who can imagine," he says. Since 2006, many laboratories have been exploring other kinds of metamaterials that don"t involve just visible light. In fact, scientists are finding that almost any kind of wave may respond to metamaterials. At the Polytechnic University of Valencia in Spain, Jose Sanchez-Dehesa is working with acoustics, or the science of sound. Just as an invisibility cloak shuffles waves of light, an "acoustic" cloak would shuffle waves of sound in a way that"s not found in nature. In an orchestra hall, for example, an acoustic cloak could redirect the sound waves-so someone sitting behind a column would hear the same concert as the rest of the audience, without distortion. Sanchez-Dehesa, an engineer, recently showed that it"s possible to build such an acoustic cloak, though he doubts we"ll see one any time soon. "In principle, it is possible," he says, but it might be impossible to make one, he adds. Other scientists are looking into ways to use larger metamaterials as shields around islands or oil rigs as protection from tsunamis. A tsunami is a giant, destructive wave. The metamaterial would redirect the tsunami around the rig or island, and the wave would resume its journey on the other side without causing any harm.

单选题{{B}}第二篇{{/B}} {{B}}How to Forgive{{/B}} To forgive may be divine, but no one ever said it was easy. When someone has deeply hurt you, it can be extremely difficult to let go of your {{U}}grudge.{{/U}} But forgiveness is possible—and it can be surprisingly beneficial to your physical and mental health. “People who forgive show less depression, anger and stress and more hopefulness,” says Frederic Luskin, Ph. D., author of Forgive for Good (Harper Collins, 2002). “So it can help save on the wear and tear on our organs, reduce the wearing out of the immune system and allow people to feel more vital.” So how do you start the healing? Try following these steps: Calm yourself. To defuse your anger, try a simple stress-management technique. “Take a couple of breaths and think of something that gives you pleasure: a beautiful scene in nature, someone you love,” Luskin says. Don’t wait for an apology. “Many times the person who hurt you has no intention of apologizing,” Luskin says. “They may have wanted to hurt you or they just don’t see things the same way. So if you wait for people to apologize, you could be waiting an awfully long time.” Keep in mind that forgiveness does not necessarily mean reconciliation with the person who upset you or condoning of his or her action. Take the control away from your offender. Mentally replaying your hurt gives power to the person who caused you pain. “Instead of focusing on your wounded feelings, learn to look for the love, beauty and kindness around you,” Luskin says. Try to see things from the other person’s perspective. If you empathize with that person, you may realize that he or she was acting out of ignorance, fear—even love. To gain perspective, you may want to write a letter to yourself from your offender’s point of view. Recognize the benefits of forgiveness. Research has shown that people who forgive report more energy, better appetite and better sleep patterns. Don’t forget to forgive yourself. “For people, forgiving themselves is the biggest challenge,” Luskin says. “But it can rob you of your self-confidence if you don’t.”

单选题No fasteners will be used in building A3XX because all components will be welded together.

单选题The telephone system is no longer {{U}}operative{{/U}}. A. flowing B. moving C. rotating D. working

单选题The first question is how hest to separate clean element—glass containers, plastics, and some paper and metal containers that is relatively clean when discarded-from mixed refuse (废料, 垃圾). This clean element is the main target for Britain's recyclers. The method of collection is important because manufacturers will not reuse collected material unless it is clean and available in sufficient quantities. A bewildering assortment(混合) of different collection schemes operates in the rest of Europe, and pilot schemes are now under way in many British cities. Recycling is possible only whenA. it is monitored by the government.B. different collection schemes operate.C. there is enough clean material.D. there is a small amount of clean material.

单选题Denny His nickname is Denny". He weighs 400 pounds; he is fearless and he never goes to sleep on the job. An ideal security guard? For many situations he may be. And if he"s so good that you wish you had a dozen like him, just place your order. Denny is a robot guard. Denny can detect, within a 150-thor radius, the presence of anything or anybody that shouldn"t be there. Its swiveling (旋转) head contains microwave and infrared sensors that can detect people as well as smoke. In future editions the head will also contain sensors that can smell the weak smell of a human body. A high-resolution TV camera in Denny"s head is on at all time. When something unexpected comes into view, the TV transmitter switches on. Thus the human overseer (看管人) in the control center sees the sudden appearance of a picture on the monitor screen. At the same time the picture is automatically videotaped. Normal speed of the robot guards is about one mile an hour, and they can even talk: "you have been detected," warns the voice from the clever guard. Denny is designed to patrol corridors and other areas after lock-down hours (of course, he can work round the clock when necessary), not to move among people. If, say, a prisoner does get near the corridor where he should not be, it"ll immediately tell its base station by radio. Denny has understandable limitations. He can"t open doors or watch stairs, for example, or distinguish a friend from an enemy. Thus he will have to go about unarmed. And he won"t be able to replace human security guards where people move about freely.

单选题It is not possible for people to {{U}}remember{{/U}} everthing that they have thought.

单选题{{B}}第三篇{{/B}} Egypt Felled by Famine Even ancient Egypts mighty pyramid builders were powerless in the face of the famine that helped bring down their civilian around 2180 BC. Now evidence gleaned(搜集) from mud deposited by the River Nile suggests that a shift in climate thousands of kilometers to the south was ultimately to blem -- and the same or worse could happen today. The ancient Egyptians depended on the Niles annual floods to irrigate their crops. But any change in climate that pushed the African monsoons(季风)southwards out of Ethiopia would have diminished these floods. Dwindling(逐渐变少；使变少)rains in the Ethiopian highlands would have meant fewer plants to establish the soil. When rain did fall it would have washed large amounts of soil into the Blue Nile and into Egypt, along with sediment(沉积；沉积物)from the White Nile. The Blue Nile mud has a different isotope signature(签名；特征) from that of the White Nile. So by analyzing isotope(同位素；核素)differences in mud deposited in the Nile Delta, Michael Krom of Leeds University worked out what proportion of sediment came from each branch of the river. Krom reasons that during periods of drought, the amount of the Blue Nile mud in the river would be relatively high. He found that one of these periods, from 4,500 to 4,200 years ago, immediately predates the fall of the Egypts Old Kingdom. The weakened waters would have been catastrophic for the Egyptians. Changes that affect food supply dont have to be very large to have a ripple effect in societies, says Bill Ryan of the Lamont Doherty Earth Observatory(天文台)in New York. "Similar events today could be even more devastating, " says team member Daniel Stanley, a geoarchaeologist(地质考古学家) from the Smithsonian Institution in Washington, D. C. "Anything humans do to shift the climate belts would have an even worse effect along the Nile system because the populations have increased dramatically. "

单选题The chairman {{U}}proposed{{/U}} that we should stop the meeting

单选题The book took ten years of thorough research.A. basicB. socialC. majorD. careful

单选题The whole idea to build a deluxe hotel here sounds {{U}}insane{{/U}} to me.

单选题He was incredibly rich.

单选题He is renowned for his skill.

单选题Some Sleep Drugs Do More Than Make You Sleep The United States Food and Drug Administration(美国食品药品管理局) has ordered companies to place strong new warnings on thirteen drugs that treat sleep disorders, It also ordered the makers of the sleeping pills to provide information for patients explaining how to safely use the drugs. Last Wednesday, the FDA announced that some of these drugs can have unexpected and dangerous effects. These include the risk of life-threatening allergic (过敏性的) reactions. They also include rare incidents of strange behavior. These include people cooking food, eating and even driving while asleep. The patients later had no memory of doing these activities while asleep. Last year, a member of the United States Congress said he had a sleep-driving incident. Patrick Kennedy, a representative from Rhode Island, crashed his car into a security barrier near the building where lawmakers meet. The accident happened in the middle of the night and no one was hurt. Mr. Kennedy said he had earlier taken a sleep medicine. He said he was also being treated with a stomach sickness drug that can cause sleepiness. The Food and Drug Administration did not say in its announcement how many cases of sleep-driving it has documented. However, the New York Times reported last year about people who said they had strange sleep events after taking the drug Ambien. Some reported sleep-driving and sleep-walking. Others said they found evidence after waking in the morning that they had cooked food or eaten in their sleep. But they had no memory of carrying out the activities. A Food and Drug Administration official says that these serious side effects of sleep disorder drugs appear to be rare. But, he also said there are probably more cases than are reported. He said the agency believes the risk of such behaviors could be reduced if people take the drugs as directed and do not drink alcohol while taking the drugs. The Food and Drug Administration has advised drug companies to carry out studies to investigate the problem.

单选题What were the (consequences) of the decision she had made?

单选题Louis Sullivan, a famous American architect, varied his structures to {{U}}suit{{/U}} the local climate.

单选题{{B}}第二篇{{/B}} The use of heat pumps has been held back largely by skepticism about advertisers' claims that heat pumps can provide as many as two units of thermal energy for each unit of electrical energy used, thus apparently contradicting the principle of energy conservation. Heat pumps circulate a fluid refrigerant(致冷剂) that cycles alternatively from its liquid phase to its vapor phase in a closed loop. The refrigerant, starting as a low-temperature, lowpressure vapor, enters a compressor 'driven by an electric motor. The refrigerant leaves the compressor as a hot, dense vapor and flows through a heat exchanger called the condenser, which transfers heat from the refrigerant to a body of air. Now the refrigerant, as a high-pressure, cooled liquid confronts a flow restriction which causes the pressure to drop. As the pressure falls, the refrigerant expands and partially vaporizes, becoming chilled. It then passes through a second heat exchanger, the evaporator, which transfers heat from the air to the refrigerant, reducing the temperature o{ this second body of air. Of the two heat exchangers, one is located inside, and the other one outside the house, so each is in contact with a different body of air: room air and outside air, respectively. The flow direction of refrigerant through a heat pump is controlled by valves. When the refrigerant flow is reversed, the heat exchangers switch function. This flow-reversal capability allows heat exchangers switch function. This flow-reversal capability allows heat pumps either to heat or cool room air. Now, if under certain conditions a heat pump puts out more thermal energy than it consumes in electrical energy, has the law of energy conservation been challenged? No, not even remotely: the additional input of thermal energy into the circulating refrigerant via the evaporator accounts for the difference in the energy equation. Unfortunately, there is one real problem. The heating capacity of a heat pump decreases as the outdoor temperature falls. The drop in capacity is caused by the lessening amount of refrigerant mass moved through the compressor at one time. The heating capacity is proportional to this mass flow rate: the less the mass of refrigerant being compressed, the less the thermal load it can transfer through the heat-pump cycle. The volume {low rate of refrigerant vapor through the single-speed rotary compressor used in heat pumps is approximately constant. But cold refrigerant vapor entering a compressor is at lower pressure than warmer vapor. Therefore, the mass of cold refrigerant—and thus the thermal energy it carries—is less than ii the refrigerant vapor were warmer before compression. Here, then, lies a genuine drawback of heat pumps: in extremely cold climates—where the most heat is needed—heat pumps are least able to supply enough heat.