备考2021年高考英语一轮复习31：说明文类阅读理解

    According to a recent study in the Journal of Consumer Research, both the size and consumption habits of our eating companions can influence our food intake. And contrary to existing research that says you should avoid eating with heavier people who order large portions(份), it's the beanpoles with big appetites you really need to avoid.

    To test the effect of social influence on eating habits, the researchers conducted two experiments. In the first, 95 undergraduate women were individually invited into a lab to ostensibly(表面上)participate in a study about movie viewership. Before the film began, each woman was asked to help herself to a snack. An actor hired by the researchers grabbed her food first. In her natural state, the actor weighed 105 pounds. But in half the cases she wore a specially designed fat suit which increased her weight to 180 pounds.

    Both the fat and thin versions of the actor took a large amount of food. The participants followed suit, taking more food than they normally would have. However, they took significantly more when the actor was thin.

    For the second test, in one case the thin actor took two pieces of candy from the snack bowls. In the other case, she took 30 pieces. The results were similar to the first test: the participants followed suit but took significantly more candy when the thin actor took 30 pieces.

    The tests show that the social environment is extremely influential when we're making decisions. If this fellow participant is going to eat more, so will I. Call it the "I'll have what she's having" effect. However, we'll adjust the influence. If an overweight person is having a large portion, I'll hold back a bit because I see the results of his eating habits. But if a thin person eats a lot, I'll follow suit. If he can eat much and keep slim, why can't I?

How to Use a Modern Public Library

    Has it been a while since your last visit to a public library? If so, you may be surprised to learn that libraries have changed for the better. It's been years since they were dusty little rooms with books. They have transformed themselves into places where you can develop your love of knowledge meet interesting people, or find out how to start a business.

    Check out a book. While libraries still loan out(出借)books, you'll find it easier to get a copy of whatever you're looking for, thanks to a cooperative network of area libraries. Via such networks, libraries share their books with each other through the use of delivery vehicles. Once the book you've requested is delivered to the nearest branch, they will inform you by e-mail, so you can pick it up.

    Check out other items. The library is now a multimedia zone, loaded with information in many formats(载体形式). You can borrow movies on DVDs, music on CDs, and popular magazines. Some libraries even loan out toys and games. If a popular magazine you want isn't offered and the library keeps a list of such requests, they may bring it in when enough interest is shown.

    Join targeted reading groups. Libraries will often hold reading-group sessions targeted to various age groups. Perhaps you'd like to learn a language or improve your English. The library may sponsor a language group you could join. If you have difficulties reading, ask about special reading opportunities. Your library might be able to accommodate you. And you might find it relaxing to bring your small kid to a half-hour Story Time while you sit quietly in a corner with a good book.

    Start a business using the help of your local library. If you want to have a business of your own, your local library can become a launch space for it. In library books and computers, you can find information on starting a business. Many libraries will help you with locally supplied information about business management shared through chambers of commerce(商会)and government agencies, and they will offer printing, faxing and database services you need.

    For people, who are interested in sound, the field of sound technology is definitely making noise. In the past, sound engineers worked in the back rooms of recording studios, but many of today's sound professionals are sharing their knowledge and experience with professionals in other fields to create new products based on the phenomenon we call sound.

    Sound can be used as a weapon. Imagine that a police officer is chasing a thief. The thief tries to escape. And the officer can't let him get away. He pulls out a special device, points it at the suspect, and switches it on. The thief drops to the ground. This new weapon is called a Long Range Acoustic Device(LRAD, 远程定向声波发射器). It produces a deafening sound so painful that it temporarily disables a person. The noise from the LRAD is directed like a ray of light and travels only into the ears of that person, but it is not deadly.

    For those who hunger for some peace and quiet, sound can now create silence. Let's say you are at the airport, and the little boy on the seat next to you is humming(哼唱) a short commercial song. He hums it over and over again, and you are about to go crazy. Thanks to the Silence Machine, a British invention, you can get rid of the sound without upsetting the boy or his parents. One may wonder how the Silence Machine works. Well, it functions by analyzing the waves of the incoming sound and creating a second set of outgoing waves. The two sets of waves cancel each other out. Simply turn the machine or point it at the target, and your peace and quiet comes back.

    Directed sound is a new technology that allows companies to use sound in much the same way spotlights(聚光灯) are used in the theater. A spotlight lights up only one section of a stage; similarly, "spotsound" creates a circle of sound in on targeted area. This can be useful for businesses such as restaurants and stores because it offers a new way to attract customers. Restaurants can offer a choice of music along with the various food choices on the menu, allowing customers more control over the atmosphere in which they are dining. Directed sound is also beginning to appear in shopping centers and even at homes.

    The traffic signals along Factoria Boulevard in Bellevue, Washington, generally don't flash the same length of green twice in a row, especially at rush hour. At 9:30am, the full red/yellow/green signal cycle might be 140 seconds. By 9:33am, a burst of additional traffic might push it to 145 seconds. Less traffic at 9:37am could push it down to 135. Just like the traffic itself, the timing of the signals changes.

That is by design. Bellevue, a fast-growing city just east of Seattle, uses a system that is gaining popularity around the US: intersection(十字路口) signals that can adjust in real time to traffic conditions. These lights, known as adaptive signals, have led to significant declines in both the trouble and cost of travels between work and home.

    "Adaptive signals can make sure that the traffic demand that is there is being addressed," says Alex Stevanovic, a researcher at Florida Atlantic University.

    For all of Bellevue's success, adaptive signals are not a cure-all for jammed roadways. Kevin Balke, a research engineer at the Texas A&M University Transportation Institute, says that while smart lights can be particularly beneficial for some cities, others are so jammed that only a sharp reduction in the number of cars on the road will make a meaningful difference. "It's not going to fix everything, but adaptive signals have some benefits for smaller cities," he says.

In Bellevue, the switch to adaptive signals has been a lesson in the value of welcoming new approaches. In the past, there was often an automatic reaction to increased traffic: just widen the roads, says Mark Poch, the Bellevue Transportation Department's traffic engineering manager. Now he hopes that other cities will consider making their streets run smarter instead of just making them bigger.

    Challenging work that requires lots of analytical thinking, planning and other managerial skills might help your brain stay sharp as you age, a study published Wednesday in the journal Neurology suggests.

    Researchers from the University of Leipzig in Germany gathered more than 1, 000 retired workers who were over age 75 and assessed the volunteers' memory and thinking skills through a battery of tests. Then, for eight years, the scientists asked the same group to come back to the lab every 18 months to take the same sorts of tests.

    Those who had held mentally stimulating(刺激), demanding jobs before retirement tended to do the best on the tests. And they tended to lose cognitive(认知) function at a much slower rate than those with the least mentally challenging jobs. The results held true even after the scientists accounted for the participants' overall health status.

    "This works just like physical exercise," says Francisca Then, who led the study. "After a long run, you may feel like you're in pain, you may feel tired. But it makes you fit. After a long day at work-sure, you will feel tired, but it can help your brain stay healthy. "

    It's not just corporate jobs, or even paid work that can help keep your brain fit, Then points out. A waiter's job, for example, that requires multitasking, teamwork and decision-making could be just as stimulating as any high-level office work. And "running a family household requires high-level planning and coordinating(协调), " she says. "You have to organize the activities of the children and take care of the bills and groceries."

    Of course, our brains can decline as we grow older for lots of reasons-including other environmental influences or genetic factors. Still, continuing to challenge yourself mentally and keeping your mind busy can only help.

    Sometimes it's hard to let go. For many British people, that can apply to institutions and objects that represent their country's past-age-old castles, splendid homes… and red phone boxes.

    Beaten first by the march of technology and lately by the terrible weather in junkyards (废品场), the phone boxes representative of an age are now making something of a comeback. Adapted in imaginative ways, many have reappeared on city streets and village greens housing tiny cafes, cellphone repair shops or even defibrillator machines (除颤器).

    The original iron boxes with the round roofs first appeared in 1926. They were designed by Giles Gilbert Scott, the architect of the Battersea Power Station in London. After becoming an important part of many British streets, the phone boxes began disappearing in the 1980s, with the rise of the mobile phone sending most of them away to the junkyards.

    About that time, Tony Inglis' engineering and transport company got the job to remove phone boxes from the streets and sell them out. But Inglis ended up buying hundreds of them himself, with the idea of repairing and selling them. He said that he had heard the calls to preserve the boxes and had seen how some of them were listed as historic buildings.

    As Inglis and, later other businessmen, got to work, repurposed phone boxes began reappearing in cities and villages as people found new uses for them. Today, they are once again a familiar sight, playing roles that are often just as important for the community as their original purpose.

    In rural areas, where ambulances can take a relatively long time to arrive, the phone boxes have taken on a lifesaving role. Local organizations can adopt them for l pound, and install defibrillators to help in emergencies.

    Others also looked at the phone boxes and saw business opportunities. LoveFone, a company that advocates repairing cellphones rather than abandoning them, opened a mini workshop in a London phone box in 2016.

    The tiny shops made economic sense, according to Robert Kerr, a founder of LoveFone. He said that one of the boxes generated around $13,500 in revenue a month and cost only about $400 to rent.

    Inglis said phone boxes called to mind an age when things were built to last. I "like what they are to people, and I enjoy bringing things back," he said.

    For those who can stomach it, working out before breakfast may be more beneficial for health than eating first, according to a study of meal timing and physical activity.

Athletes and scientists have long known that meal timing affects performance. However, far less has been known about how meal timing and exercise might affect general health.

    To find out, British scientists conducted a study. They first found 10 overweight and inactive but otherwise healthy young men, whose lifestyles are, for better and worse, representative of those of most of us. They tested the men's fitness and resting metabolic (新陈代谢的) rates and took samples (样品) of their blood and fat tissue.

    Then, on two separate morning visits to the scientists' lab, each man walked for an hour at an average speed that, in theory should allow his body to rely mainly on fat for fuel. Before one of these workouts, the men skipped breakfast, meaning that they exercised on a completely empty stomach after a long overnight fast (禁食). On the other occasion, they ate a rich morning meal about two hours before they started walking.

Just before and an hour after each workout, the scientists took additional samples of the men's blood and fat tissue.

    Then they compared the samples. There were considerable differences. Most obviously, the men displayed lower blood sugar levels at the start of their workouts when they had skipped breakfast than when they had eaten. As a result, they burned more fat during walks on an empty stomach than when they had eaten first. On the other hand, they burned slightly more calories (卡路里), on average, during the workout after breakfast than after fasting.

    But it was the effects deep within the fat cells that may have been the most significant, the researchers found. Multiple genes behaved differently, depending on whether someone had eaten or not before walking. Many of these genes produce proteins (蛋白质) that can improve blood sugar regulation and insulin (胰岛素) levels throughout the body and so are associated with improved metabolic health. These genes were much more active when the men had fasted before exercise than when they had breakfasted.

The implication of these results is that to gain the greatest health benefits from exercise, it may be wise to skip eating first.

    I was in the middle of the Amazon (亚马逊) with my wife, who was there as a medical researcher. We flew on a small plane to a faraway village. We did not speak the local language, did not know the customs, and more often than not, did not entirely recognize the food. We could not have felt more foreign.

    We were raised on books and computers, highways and cell phones, but now we were living in a village without running water or electricity It was easy for us to go to sleep at the end of the day feeling a little misunderstood.

    Then one perfect Amazonian evening, with monkeys calling from beyond the village green, we played soccer. I am not good at soccer, but that evening it was wonderful. Everyone knew the rules. We all spoke the same language of passes and shots. We understood one another perfectly. As darkness came over the field and the match ended, the goal keeper, Juan, walked over to me and said in a matter-of-fact way, "In your home, do you have a moon too?" I was surprised.

    After I explained to Juan that yes, we did have a moon and yes, it was very similar to his, I felt a sort of awe (敬畏) at the possibilities that existed in his world. In Juan's world, each village could have its own moon. In Juan's world. the unknown and undiscovered was vast and marvelous. Anything was possible.

    In our society, we know that Earth has only one moon. We have looked at our planet from every angle and found all of the wildest things left to find. I can, from my computer at home, pull up satellite images of Juan's village. There are no more continents and no more moons to search for, little left to discover. At least it seems that way.

    Yet, as I thought about Juan's question, I was not sure how much more we could really rule out. I am, in part, an ant biologist, so my thoughts turned to what we know about insect life and I knew that much in the world of insects remains unknown. How much, though? How ignorant (无知的) are we? The question of what we know and do not know constantly bothered me.

    I began collecting newspaper articles about new species, new monkey, new spider…, and on and on they appear. My drawer quickly filled. I began a second drawer for more general discoveries: new cave system discovered with dozens of nameless species, four hundred species of bacteria found in the human stomach. The second drawer began to fill and as it did I wondered whether there were bigger discoveries out there, not just species, but life that depends on things thought to be useless, life even without DNA. I started a third drawer for these big discoveries. It fills more slowly, but all the same, it fills.

    In looking into the stories of biological discovery, I also began to find something else, a collection of scientists, usually brilliant occasionally half-mad, who made the discoveries. Those scientists very often see the same things that other scientists see, but they pay more attention to them, and they focus on them to the point of exhaustion (穷尽), and at the risk of the ridicule of their peers. In looking for the stories of discovery, I found the stories of these people and how their lives changed our view of the world.

    We are repeatedly willing to imagine we have found most of what is left to discover. We used to think that insects were the smallest organisms (生物), and that nothing lived deeper than six hundred meters. Yet, when something new turns up, more often than not, we do not even know its name.

    With the young unable to afford to leave home and the old at risk of isolation(孤独), more families are choosing to live together.

    The doorway to peace and quiet, for Nick Bright at least, leads straight to his mother-in-law, she lives on the ground floor, while he lives upstairs with his wife and their two daughters.

    Four years ago they all moved into a three-storey Victorian house in Bristol — one of a growing number of multigenerational families in the UK living together under the same roof. They share a front door and a washing machine, but Rita Whitehead has her own kitchen, bathroom, bedroom and living room on the ground floor.

    "We floated the idea to my mum of sharing at a house," says Kathryn Whitehead. Rita cuts in: "We spoke more with Nick because I think it's a big thing for Nick to live with his mother-in-law."

    And what does Nick think? "From my standpoint, it all seems to work very well. Would I recommend it? Yes, I think I would."

    It's hard to tell exactly how many people agree with him, but research indicates that the numbers have been rising for some time. Official reports suggest that the number of households with three generations living together had risen from 325,000 in 2002 to 419,000 in 2013.

    Other varieties of multigenerational family are more common. Some people live with their elderly parents; many more adult children are returning to the family home, if they ever left. It is said that about 20% of 25-34-year-olds live with their parents, compared with 16% in 1991.The total number of all multigenerational households in Britain is thought to be about 1.8 million.

    Stories like that are more common in parts of the world where multigenerational living is more firmly rooted. In India, particularly outside cities, young women are expected to move in with their husband's family when they get married.

    We are the products of evolution, and not just evolution that occurred billions of years ago. As scientists look deeper into our genes (基因), they are finding examples of human evolution in just the past few thousand years. People in Ethiopian highlands have adapted to living at high altitudes. Cattle -raising people in East Africa and northern Europe have gained a mutation (突变) that helps them digest milk as adults.

    On Thursday in an article published in Cell, a team of researchers reported a new kind of adaptation - not to air or to food, but to the ocean. A group of sea-dwelling people in Southeast Asia have evolved into better divers. The Bajau, as these people are known, number in the hundreds of thousands in Indonesia, Malaysia and the Philippines. They have traditionally lived on houseboats; in recent times, they've also built houses on stilts (支柱) in coastal waters. "They are simply a stranger to the land," said Redney C. Jubilado, a University of Hawaii researcher who studies the Bajau.

    Dr. Jubilado first met the Bajau while growing up on Samal Island in the Philippines. They made a living as divers, spearfishing or harvesting shellfish. "We were so amazed that they could stay underwater much longer than us local islanders," Dr. Jubilado said. "I could see them actually walking under the sea."

    In201, Melissa Ilardo, then a graduate student in genetics at the University of Copenhagen, heard about the Bajau. She wondered if centuries of diving could have led to the evolution of physical characteristics that made the task easier for them. "it seemed like the perfect chance for natural selection to act on a population," said Dr. Ilardo. She also said there were likely a number of other genes that help the Bajau dive.

    Returning to a book you've read many times can feel like drinks with an old friend. There's a welcome familiarity — but also sometimes a slight suspicion that time has changed you both, and thus the relationship. But books don't change, people do. And that's what makes the act of rereading so rich and transformative.

    The beauty of rereading lies in the idea that our bond with the work is based on our present mental register. It's true, the older I get, the more I feel time has wings. But with reading, it's all about the present. It's about the now and what one contributes to the now, because reading is a give and take between author and reader. Each has to pull their own weight.

    There are three books I reread annually The first, which I take to reading every spring is Emest Hemningway's A Moveable Feast. Published in 1964, it's his classic memoir of 1920s Paris. The language is almost intoxicating (令人陶醉的), an aging writer looking back on an ambitious yet simpler time. Another is Annie Dillard's Holy the Firm, her poetic 1975 ramble (随笔) about everything and nothing. The third book is Julio Cortazar's Save Twilight: Selected Poems, because poetry. And because Cortazar.

    While I tend to buy a lot of books, these three were given to me as gifs, which might add to the meaning I attach to them. But I imagine that, while money is indeed wonderful and necessary, rereading an author's work is the highest currency a reader can pay them. The best books are the ones that open further as time passes. But remember, it's you that has to grow and read and reread in order to better understand your friends.

    Race walking shares many fitness benefits with running, research shows, while most likely contributing to fewer injuries. It does, however, have its own problem.

    Race walkers are conditioned athletes. The longest track and field event at the Summer Olympics is the 50-kilometer race walk, which is about five miles longer than the marathon. But the sport's rules require that a race walker's knees stay straight through most of the leg swing and one foot remain in contact (接触) with the ground at all times. It's this strange form that makes race walking such an attractive activity, however, says Jaclyn Norberg, an assistant professor of exercise science at Salem State University in Salem, Mass.

    Like running, race walking is physically demanding, she says, According to most calculations, race walkers moving at a pace of six miles per hour would burn about 800 calories(卡路里) per hour, which is approximately twice as many as they would burn walking, although fewer than running, which would probably burn about 1,000 or more calories per hour.

    However, race walking does not pound the body as much as running does, Dr. Norberg says. According to her research, runners hit the ground with as much as four times their body weight per step, while race walkers, who do not leave the ground, create only about 1.4 times their body weight with each step.

    As a result, she says, some of the injuries associated with running, such as runner's knee, are uncommon among race walkers. But the sport's strange form does place considerable stress on the ankles and hips, so people with a history of such injuries might want to be cautious in adopting the sport. In fact, anyone wishing to try race walking should probably first consult a coach or experienced racer to learn proper technique, she says. It takes some practice.

    The connection between people and plants has long been the subject of scientific research. Recent studies have found positive effects. A study conducted in Youngstown, Ohio, for example, discovered that greener areas of the city experienced less crime. In another, employees were shown to be 15% more productive when their workplaces were decorated with houseplants.

    The engineers at the Massachusetts Institute of Technology (MIT) have taken it a step further changing the actual composition of plants in order to get them to perform diverse, even unusual functions. These include plants that have sensors printed onto their leaves to show when they're short of water and a plant that can detect harmful chemicals in groundwater. "We're thinking about how we can engineer plants to replace functions of the things that we use every day," explained Michael Strano, a professor of chemical engineering at MIT.

    One of his latest projects has been to make plants grow (发光) in experiments using some common vegetables. Strano's team found that they could create a faint light for three-and-a-half hours. The light, about one-thousandth of the amount needed to read by, is just a start. The technology, Strano said, could one day be used to light the rooms or even to turn tree into self-powered street lamps. in the future, the team hopes to develop a version of the technology that can be sprayed onto plant leaves in a one-off treatment that would last the plant's lifetime. The engineers are also trying to develop an on and off" switch" where the glow would fade when exposed to daylight.

    Lighting accounts for about 7% of the total electricity consumed in the US. Since lighting is often far removed from the power source (电源)—such as the distance from a power plant to street lamps on a remote highway-a lot of energy is lost during transmission (传输). Glowing plants could reduce this distance and therefore help save energy.

    Some parents will buy any high-tech toy if they think it will help their child, but researchers said puzzles help children with math-related skills.

    Psychologist Susan Levine, an expert on mathematics development in young children the University of Chicago, found children who play with puzzles between ages 2 and 4 later develop better spatial skills. Puzzle play was found to be a significant predictor of cognition(认知) after controlling for differences in parents' income, education and the amount of parent talk, Levine said.

    The researchers analyzed video recordings of 53 child-parent pairs during everyday activities at home and found children who play with puzzles between 26 and 46 months of age have better spatial skills when assessed at 54 months of age.

    "The children who played with puzzles performed better than those who did not, on tasks that assessed their ability to rotate(旋转)and translate shapes," Levine said in a statement.

    The parents were asked to interact with their children as they normally would, and about half of children in the study played with puzzles at one time. Higher-income parents tended to have children play with puzzles more frequently, and both boys and girls who played with puzzles had better spatial skills. However, boys tended to play with more complex puzzles than girls, and the parents of boys provided more spatial language and were more active during puzzle play than parents of girls.

    The findings were published in the journal Developmental Science.

    When you were trying to figure out what to buy for the environmentalist on your holiday list, fur probably didn't cross your mind. But some ecologists and fashion (时装) enthusiasts are trying to bring back the market for fur made from nutria(海狸鼠).

    Unusual fashion shows in New Orleans and Brooklyn have（showcased）nutria fur made into clothes in different styles. "It sounds crazy to talk about guilt-free fur-unless you understand that the nutria are destroying vast wetlands every year", says Cree McCree, project director of Righteous Fur.

    Scientists in Louisiana were so concerned that they decided to pay hunters $5 a tail. Some of the fur ends up in the fashion shows like the one in Brooklyn last month.

    Nutria were brought there from Argentina by fur farmers and let go into the wild. "The ecosystem down there can't handle this non-native species (物种) .It's destroying the environment. It's them or us." says Michael Massimi, an expert in this field.

    The fur trade kept nutria check for decades, but when the market for nutria collapsed in the late 1980s, the cat-sized animals multiplied like crazy.

    Biologist Edmond Mouton runs the nutria control program for Louisiana. He says it's not easy to convince people that nutria fur is green, but he has no doubt about it. Hunters bring in more than 300,000 nutria tails a year, so part of Mouton's job these days is trying to promote fur.

    Then there's Righteous Fur and its unusual fashion. Morgan says," To give people a guilt-free option that they can wear without someone throwing paint on them—1 think that's going to be a massive thing, at least here in New York." Designer Jennifer Anderson admits it took her a while to come around to the opinion that using nutria fur for her creations is morally acceptable. She trying to come up with a lable to attach to nutria fashions to show it is eco-friendly.

    Summer is here, and with it comes a chance you'll get too much sun. While there's no cure for sunburn, a small but fascinating new study suggests taking large amounts of vitamin D after exposure may prevent the associated redness and inflammation (发炎) .

    In the paper, researchers exposed 20 volunteers to a light resembling solar radiation to induce a sunburn on a small piece of skin. They then gave the ''burn victims'' large amounts of vitamin D, and followed up with participants one, two and three days (and a week) later to measure skin redness and thickness. The researchers found that vitamin D decreased inflammation and redness, compared with taking a placebo (安慰剂) . And this effect increased in proportion to how much was consumed. Vitamin D also appears to increase the activity of a gene called arginase-1, which is involved in tissue repair and healing. Taking 50, 000 international units (IU) of vitamin D--125 times the recommended daily allowance-led to a significant reduction in redness and inflammation, compared with the placebo. Those who took 100,000 IU had even less redness and pain; and those who took 200, 000 IU had the greatest reduction in inflammation.

    This is the first study to show vitamin D can reduce inflammation, and suggests that it ''could potentially help prevent sunburn, '' says senior author Kurt Lu, a physician scientist and assistant professor at Case Western Reserve University.

    It used to be thought vitamin D was primarily involved in building healthy bones and muscles, but recent research has found it has many more roles, including influencing inflammation, such as the kind associated with sunburns.

    So, if you get burned, should you take a lot of vitamin D? The study authors don't recommend it. ''I think that's probably not a good idea and not well established by this study, '' says Barbara Gilchrest, a physician scientist at Massachusetts General Hospital. Such large amounts, if taken repeatedly, have the potential to cause vitamin D toxicity (毒性) .

    Scientists in the U.S. have created an artificial sunflower less than 0. 04 inches wide that can bend towards a light source and harvest solar energy. The flowers were found to be about 400 percent more efficient than other equipment, making them promising technology for solar power potentially even as a power source for solar-based spaceships.

    The team, led by researchers from the University of California, Los Angeles, was looking to improve the efficiency of solar cells by modeling after a feature of nature-phototropism. This is where a plant adjusts itself to face the sun, getting the most amount of energy it can get. In a study published in Nature Nanotechnology, the team said it was a ''big challenge''.

    However, this problem has now been overcome. The team has developed a polymer (聚合物) that is responsive to being simulated by light, The system, which they have named SunBOT for short, is able to instantly explore and track a light source. It can do this across a range of temperatures without power supply or any human intervention.

    The researchers used the polymer to create a ''stem''. Then they placed a material commonly used in solar cells on its top, representing the ''flower''. When the team shone a light at the SunBOTs, the polymer began heating up and shrinking, causing the stem to bend so the flower faced the light.

    The researchers tested their artificial sunflowers to see how efficient they were at harvesting solar energy Findings showed they were up to 400 percent more effective than non-phototrophic materials.

    The practical applications of SunBOTs are some way off. The study shows a proof of concept, but the technology will need to be scaled up to be used commercially. However, the team is confident it could one day be used a across a broad range of industries.

    This work may be useful for solar harvesters signal revere smart windows, self-contained robotics solar sails for spaceships and intelligent energy generation (for example, solar cells and biofuels), the scientific team said.

    Can you think of a day without music? We can hear music everywhere: in the streets and at home, over the radio and on TV, in the shops and in the parks. People all over the world are fond of music. They listen to music, they dance to music, and they learn to play musical instruments.

    Music isn't' only combination of pleasant sounds. It is an art which reflects life. There are lot of different kinds of music. Some of them appeared long ago, and some are modern. Folk music appeared long ago, but it is still alive. Folk songs are very pleasant to listen to. Classical music is often associated with the music of the past. Rap is a modern musical style where the singer speaks or shouts the words in time to music with a steady beat.

Great Britain has produced more popular music stars than any other country. British groups often set new trends in music. New styles, groups and singers continue to appear. Many of the new bands have been able to use changes in technology to develop their music such as computerised drum machines, synthesisers and other electronic instruments.

    Tastes differ. So people's musical interests range from pop and rock music to classical music and opera. My favourite style of music is pop music, because it is full of energy. When I listen to pop music it makes me remember happy times and forget the problems of everyday life. I also enjoy listening to classical music. The music I hate is heavy metal, I find it noisy. When I listen to this style of music it presents to my mind pictures of dark days. My mother and father agree with my tastes in music. Though they prefer to listen to classical, they think that modern music is not too bad.

    Music appeals to our hearts. It comforts our souls and enriches our minds. Music is beauty in sounds; it is our magic source of inspiration.

    Diana Jacobs thought her family had a workable plan to pay for college for her 21-year-old twin sons: a combination of savings, income, scholarships, and a modest amount of borrowing. Then her husband lost his job, and the plan fell apart.

    "I have two kids in college, and I want to say come home. ' but at the same time I want to provide them with a good education," says Jacobs.

    The Jacobs family, did work out a solution: They asked and received more aid from the schools, and each son increased his' borrowing to the maximum amount through the federal loan (贷款) program. They will each graduate with $ 20,000 of debt, but at least they will be able to finish school.

    With unemployment rising, financial aid administrators expect to hear from more families like the Jacobses. More students are applying for aid, and more families expect to need student loans. College administrators are concerned that they will not have enough aid money to go around.

    At the same time, tuition (学费) continues to rise. A report from the National Center for Public Policy and Higher Education found that college tuition and fees increased 439% from 1982 to 2007, while average family income rose just 147%. Student borrowing has more than doubled in the last decade.

    "If we go on this way for another 25 years, we won't have an affordable system of higher education," says Patrick M. Calan, president of the center. "The middle class families have been financing it through debt. They will send kids to college whatever it takes, even if that means a huge amount of debt."

    Financial aid administrators have been having a hard time as many companies decide that student loans are not profitable enough and have stopped making them. The good news, however, is that federal loans account for about three quarters of student borrowing, and the government says that money will flow uninterrupted.