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.

单选题The Body Clock Why is it that flying to New York from London will leave you feeling less tired than flying to London from New York? The answer may be a clear case of biology not being able to keep up with technology. Deep inside the brain there is a "clock" that governs every aspect of the body's functioning: sleep and wake cycles, levels of alertness, performance, mood, hormone levels, digestion, body temperature and so on. It regulates all of these functions on a 24-hour basis and is called the biological clock. This body clock programmes us to be sleepy twice a day, between 3-5 am and again between 3-5 pm. Afternoon tea and nap are all cultural responses to our natural biological sleepiness in the afternoon. One of the major causes of the travellers' malady known as jet lag is the non-alignment of a person's internal body clock with clocks in the external world. Crossing different time zones confuses the biological clock, which then has to adjust to the new time and patterns of light and activity. To make matters more complex, not all internal body functions adjust at the same rate. So your sleep/wake may adjust to a new time zone at one rate, while your temperature adjusts at a different pace. Your digestion may be on a different schedule altogether. Though we live in a 24-hour day, the natural tendency of the body clock is to extend our day beyond 24 hours. It is contrary to our biological programming to "shrink" our day'. That is why traveling in a westward direction is more body-clock friendly than flying east. NASA studies of long haul pilots showed that westward travel was associated with significantly better sleep quantity and quality than eastward flights. When flying west, you are "extending" your day, thus traveling in the natural direction of your internal clock. Flying eastward will involve "shrinking" or reducing your day and is in direct opposition to your internal clock's natural tendency. One of the more common complaints of travelers is that their sleep becomes disrupted. There are many reasons for this, changing time zones and schedules, changing light and activity levels, trying to sleep when your body clock is programmed to be awake, disruption of the internal biological clock and working longer hours. It is often suggested that you adjust your watch as soon as you board a plane, supposedly to try to help you adjust to your destination's schedule as soon as you arrive. But it can take the body clock several days to several weeks to fully adjust to a new time zone. So, our body clock truly can "govern" us.

单选题The Polynesians found uses for many indigenous plants.

单选题We'll give every teacher Uroom/U for development.

单选题The Little Foxes , a drama by Lillian Hellman, was first produced in New York in 1939.

单选题Earthquake How does an earthquake start2 What makes an earthquake happen? The rock of the earth"s crust (地壳) may have a fault, a kind of break in the surface. The blocks which make up the earth move, and sometimes this may cause the sides of the fault to move up and down or lengthways (纵向地) against each other. When one piece of rock starts to rub on another with great force, a lot of energy is used. This energy is changed into vibrations (震动) and it is these vibrations that we reef as an earthquake. The vibrations can travel thousands of kilometers and so an earthquake in Turkey may be felt in Greece. What to do during an earthquake? At school As soon as the earthquake starts, students should get under the desks immediately and wait until the teacher tells them it is safe to come out. The teacher should, at the same time, go immediately to the teacher"s desk, get underneath (在……下面) it and stay there till the danger is over. Students must not argue with the teacher or question instructions. As soon as the tremors (震动) stop, all students should walk towards the exit and go straight to the school playground or any open space such as a square or a park. They must wait there until the teacher tells them it is safe to go. At home If you are at home when the earthquake occurs, get immediately under the table in the living room or kitchen. Choose the biggest and strongest table you can find. You must not go anywhere near the window and don"t go out onto the balcony (阳台). Once the tremors have stopped, you can come out from under the table but you must leave the building straight away. You should walk down the stairs and should not use the lift-there may be a power cut as a result of the earthquake and you could find yourself trapped inside the lift for hours. In the street If you are in the street when the earthquake takes place, do not stand near buildings, fences or walls—move away as quickly as possible arid try to find a large open space to wait in. Standing under trees could also be dangerous.

单选题The word“sustain”(paragraph 2)could be best replaced by