单选题It"s impolite to cut in when two person are holding a conversation.

单选题 Unpopular Subjects? Is there a place in today's society for the study of useless subjects in our universities? Just over 100 years ago Fitzgerald argued in a well-written letter {{U}} {{U}} 1 {{/U}} {{/U}}Nature that "Universities must be allowed to study useless subjects—{{U}} {{U}} 2 {{/U}} {{/U}}they don't, who will? He went on to use the {{U}} {{U}} 3 {{/U}} {{/U}}of Maxwell's electrodynamics (电动力学) as one case where a "useless subject" has been transformed to a useful subject. Nowadays this argument is again very much {{U}} {{U}} 4 {{/U}} {{/U}}in many universities. Indeed one suspects that it is one of those arguments that must be {{U}} {{U}} 5 {{/U}} {{/U}}anew (重新) by each generation. But now there is an added twist subjects must not only be useful, they must also be {{U}} {{U}} 6 {{/U}} {{/U}}enough that students will flock (蜂拥) to do them, and even flock to pay to do them. As universities become commercial operations, the pressure to {{U}} {{U}} 7 {{/U}} {{/U}}subjects or departments that are less popular will become stronger and stronger. Perhaps this is most strongly {{U}} {{U}} 8 {{/U}} {{/U}}at the moment by physics. There has been much {{U}} {{U}} 9 {{/U}} {{/U}}in the press of universities that are closing down physics departments and incorporate them with mathematics or engineering departments. Many scientists think otherwise. They see physics as a {{U}} {{U}} 10 {{/U}} {{/U}}science, which must be kept alive if only to {{U}} {{U}} 11 {{/U}} {{/U}}a base for other sciences and engineering. It is of their great personal concern that physics teaching and research is under {{U}} {{U}} 12 {{/U}} {{/U}}in many universities. How Can it be preserved in the rush towards commercial competition? A major turnaround (转变) in student popularity may have to {{U}} {{U}} 13 {{/U}} {{/U}}until the industrial world discovers that it needs physicists and starts paying them well. Physics is now not only unpopular; it is also "hard". We can do more about the latter by {{U}} {{U}} 14 {{/U}} {{/U}}teaching in our schools and universities. We can also {{U}} {{U}} 15 {{/U}} {{/U}}cooperative arrangements to ensure that physicists keep their research and teaching up to date.

单选题Didn't you know that the naughty girl used to skip classes?

单选题Credit Card Only Works When Spoken To A credit card that will not work unless it hears its owner"s voice could become an important weapon in the fight against fraud (欺骗), The card requires users to give a spoken password that it recognizes using a built-in voice-recognition chip. The idea is to prevent thieves using a stolen card or fraudsters using someone else"s credit card details to buy goods online. A model built by engineers at Beepcard in Santa Monica, California, represents the first attempt to pack a microphone, a loudspeaker, a battery and a voice-recognition chip into a standard-sized credit card. They are not quite there yet: the card is the length and width of an ordinary credit card, but it is still about three times as thick. The company now plans to make it thinner. The voice card is based on an earlier Beepcard technology designed to prevent fraud in online transactions. This earlier card has no microphone, but has a built-in loudspeaker that it uses to "squawk" (发出叫声) a voice ID signal via a computer"s microphone to an online server By verifying (证实) that the signal matches the card details, the server can establish that the user is not simply keying in a credit card number but actually has the card to hand. The ID code changes each time the card is used in a pre-ordered sequence that only the server knows. This prevents fraudsters recording the beeps, noting the card details and then playing back the audible ID when they key in the details later. But this earlier technology cannot prevent fraudulent use of stolen cards. The new one can. The new voice card also identifies itself by its ID squawk, but it will not do this until it has verified the legitimate (合法的) user"s spoken password. Thieves will be unable to use the card because even if they knew the password they would have to be able to copy the owner"s voice with a high degree of accuracy. The challenge for Beepcard has been to develop voice-recognition and audio circuitry that can be powered by a mini battery embedded (嵌入的) in a credit card. To maximize battery life, the electronics are only switched on when the card is being used. Pressing a button on the card"s surface prompts it to utter "say your password" in female voice. If the voice-recognition software proves that the password is authentic (真实的), it sends its ID squawk which the server then identifies, allowing the transaction to proceed.

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 manage 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 wavesso 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Henry cannot resist the{{U}} lure{{/U}} of drugs

单选题What is the best title for the passage? 　　A.

单选题Winged Robot Learns to Fly Learning how to fly took nature millions of years of trial and error—but a winged robot has cracked it in only a few hours, using the same evolutionary principles. Krister Wolff and Peter Nordin of Chalmers University of Technology (CUT) in Gothenburg, Sweden, built a winged robot and set about testing whether it could learn to fly by itself, without any pre-programmed data on what flapping is or how to do it. To begin with, the robot just twitched and jerked erratically. But, gradually, it made movements that gained height. At first, it cheated—simply standing on its wing tips was one early short cut. After three hours, however, the robot abandoned such methods in favor of a more effective flapping technique where it rotated its wings through 90 degrees and raised them before twisting them back to the horizontal and pushing down. "This tells us that this kind of evolution is capable of coming up with flying motion," says Peter Bentley, who works on evolutionary computing at University College London. But while the robot had worked out how best to produce lift, it was not about to take off. "There"s only so much that evolution can do," Bentley says. "This thing is never going to fly because the motors will never have the strength to do it," he says. The robot had metre-long wings made from balsa wood and covered with a light plastic film. Small motors on the robot let it move its wings forwards or backwards, up or down or twist them in either direction. The team attached the robot to two vertical rods, so it could slide up and down. At the start of a test, the robot was suspended by an elastic band. A movement detector measured how much lift, if any, the robot produced for any given movement. A computer program fed the robot random instructions, at the rate of 20 per second, to test its flapping abilities. Each instruction told the robot either to do nothing or to move the wings slightly in the various directions. Feedback from the movement detector let the program work out which sets of instructions were best at producing lift. The most successful ones were paired up and "offspring" sets of instructions were generated by swapping instructions randomly between successful pairs. These next generation instructions were then sent to the robot and evaluated before breeding a new generation, and the process was repeated.

单选题The Need to Remember Some people say they have no memory at all: "I just can"t remember a thing!" But of course we all have a memory. Our memory tells us who we are. Our memory helps us to make use in the present of what we have learnt in the past. In fact we have different types of memory. For example, our visual memory helps us recall facts and places. Some people have such a strong visual memory that they can remember exactly what they have seen, for example, pages of a book, as a complete picture. Our verbal(言语的) memory helps us remember words and figures we may have heard but not seen or written: Items of a shopping list, a chemical formula, dates, or a recipe. With our emotional(情感的)memory, we recall situations or places where we had; strong feelings, perhaps of happiness or unhappiness. We also have special memories for smell, taste, touch and sound, and for performing physical movements. We have two ways of storing any of these memories. Our short-term memory stores items for up to thirty seconds—enough to remember a telephone number while we dial. Our long-term memory, on the other hand, may store items for a lifetime. Older people in fact have a much biter long-term memory than short-term. They may forget what they have done only a few hours ago, but have the clearest remembrance(记忆) of when they were very young. Psychologists tell us that we only remember a few facts about our past, and that we invent the rest. It is as though we remember only the outline of a story. We then make up the details. We often do this in the way we want to remember them, usually so that we appear as the heroes of our own past, or maybe victims needing sympathy (同情).

单选题I’m sure I’ll be able to Uamuse/U myself for a few hours.

单选题George Washington Carver was esteemed for his contributions in the fields of botany and chemistry.

单选题As the industry developing in these years, most of the rivers have been contaminated by sewage (污水).

单选题Some scientists believe that dolphins have a language of their own.

单选题Our {{U}}correspondent{{/U}} Carl from South Africa will give us a brief introduction of their presidential election.

单选题Sony's Vision For The Future As the television, communications and telecommunications industries emerge, compatibility (兼容性) becomes a big issue for consumers. I think we should maintain open and compatible standards end create features particular to Sony, in other words, the system should be open but the services could be distinctive—like restaurants. The menus may be alike but the services are different. Being president of Sony Corporation, I am often asked by this question: With digital cameras and digital camcorders (摄像机), what will be the future of digital imaging? In 1997, optimists see non-traditional cameras—digital cameras— achieving sales of one million units in Japan. We are selling a new digital camera. Even though the price is quite high, it is selling well. And laser and ink-jet printers have improved greatly for printing colour pictures. But traditional pictures are still more popular than those from today's electronic cameras. Because of that, traditional cameras and digital cameras will co-exist for a long time. If you want me to sum up Sony's vision for the next few years, all I can say is that there will be a big change. We can run our business at Sony based on today's technologies w which means the digitalisation of audio and video. But beyond 2000, there will be a big change and we should be prepared. This will be the network environment. So we are preparing for a big change in technologies and for a change in the way of thinking as well. We celebrate our 50th anniversary this year (1997), and this coincides (与……一致) with what I call the transistor cycle, which has also lasted fifty years. Since we started using transistors in radios, the electronic industry has undergone a big evolution. But a new technology wave started with the invention of the microprocessor, about 14 or 15 years ago. My theory is that each business cycle lasts 50 years, with one cycle overlapping (重叠) another. The information age started 15 years ago with microprocessors and for another 10 years it will be in the takeoff stage. Like an airport, a 747 approaching the end of the runway is still gathering speed. So for information technology, for another five to seven years there will not be so much change, only increasing speed. But after that you fly. What that will mean, I cannot foresee. I'm just preparing for the takeoff stage while I'm president. The job of the next generation will be more important, I’m just in-between.

单选题 下面的短文有15处空白，亲根据短文内容为每处空白确定1个最佳选项。 Migrant Workers In the past 20 years, there has been an increasing tendency for workers to move from one country to another. {{U}}(51) {{/U}}some newly independent countries have understandably restricted most jobs to local people, others have attracted and welcomed migrant workers. This is particularly the case in the Middle East, {{U}}(52) {{/U}}increased oil incomes have enabled many countries to{{U}} (53) {{/U}}outsiders to improve local facilities. {{U}}(54) {{/U}} the Middle East has attracted oil-workers from the U. S. A. and Europe. It has brought in construction workers and technicians from many countries, {{U}}(55) {{/U}} South Korea and Japan. In view of the difficult living and working conditions in the Middle East, it is not {{U}}(56) {{/U}} that the pay is high to attract suitable (合适的)workers. Many engineers and technicians can earn at least{{U}} (57) {{/U}}money in the Middle East as they can in their own country, and this is a major attraction. An allied benefit is the low taxation or complete lack of it. This increases the net amount of pay received by visiting workers and is very popular with them. Sometimes a disadvantage has a compensating advantage. {{U}}(58) {{/U}}, the difficult living conditions often lead to increased friendship when workers have to depend on each other {{U}}(59) {{/U}} safety and comfort. {{U}}(60) {{/U}}, many migrant workers can save large sums of money partly {{U}}(61) {{/U}}the lack of entertainment facilities. The work is often complex and full of problems but this merely presents greater challenge to engineers who prefer to find solutions {{U}}(62) {{/U}} problems rather than do routine work in their home country. One major problem which {{U}}(63) {{/U}} migrant workers in the Middle East is that their jobs are temporary ones. They are nearly always on contract, so it is not easy for them to plan ahead with great confidence. This is to be expected since no country welcomes a large number of foreign workers as permanent residents. {{U}}(64) {{/U}}, migrant workers accept this disadvantage, along with others, because of the {{U}}(65) {{/U}}financial benefits that they receive.

单选题All animals can sense the very small changes in air pressure, gravity, or the magnetism of earth.

单选题In the eighteenth century the {{U}}heading{{/U}} of “natural philosophy” encompassed all of the sciences.

单选题I have been trying to {{U}}quit{{/U}} smoking. A.give up B.pick up C.build up D.take up

单选题The first navigational lights in the New World were probably lanterns hung at harbor entrances. The first lighthouse was put up by the Massachusetts Bay Colony in 1716 on Little Brewster Island at the entrance to Boston Harbor. Paid for and maintained by "light dues" levied (征收) on ships, the original beacon was blown up in 1776. Until then there were only a dozen or so true lighthouses in the colonies. Little over a century later, there were 700 lighthouses. The first eight lighthouses erected on the West Coast in the 1850s featured the same basic New England design: a Cape Cod dwelling with the tower rising from the center or standing close by. In New England and elsewhere, though, lighthouses reflected a variety of architectural styles. Since most stations in the Northeast were set up on rocky eminences (高处), enormous towers were not the rule. Some were made of stone and brick, others of wood or metal. Some stood on pilings or stilts; some were fastened to rock with iron rods. Farther south, from Maryland through the Florida Keys, the coast was low and sandy. It was often necessary to build tall towers there—massive structures like the majestic lighthouse in Cape Hatteras, North Carolina, which was lit in 1870. 190 feet high, it is the tallest brick lighthouse in the country. Not withstanding differences in construction appearance, most lighthouses in America shared several features: a light, living quarters, and sometimes a bell (or, later, a foghorn). They also had something else in common: a keeper and usually the keeper"s family. The keeper"s essential task was trimming the lantern wick (灯芯) in order to maintain a steady, bright flame. The earliest keepers came from every walk of life, they were seamen, farmers, mechanics, rough mill hands and appointments were often handed out by local customs commissioners as political plums. After the administration of lighthouse was taken over in 1852 by the United States Lighthouse Board, and agency of the Treasury Department, the keeper corps gradually became highly professional.