Hummingbirds(蜂鸟) are one of nature's most energetic fliers and the only birds to hover(盘旋) in the air by relying on their strength alone.

    Now scientists have found that it is the ratio(比值) of the bird's wing length to its width that makes them so efficient. The discovery is helping experts compete with 42 million years of natural selection to build helicopters that are increasingly efficient.

    David Lentink, an assistant professor at Stanford University in California, tested wings from 12 different species of hummingbirds, which he sourced from museums. He placed them on a machine used to test the aerodynamics(气力学) of the helicopter blades(桨叶). Professor Lentink's team used the same machine to test the blades from an advanced micro-helicopter used by the UK's army. They found that the micro-helicopter's blades are as efficient at hovering as the average hummingbirds.

    But while the micro-helicopter's blades kept pace with the average hummingbird wings, they could not keep up with the most efficient hummingbird's wing. The wings of Anna's hummingbird were found to be about 27 percent more efficient than the man-made micro- helicopter's blades.

    While Professor Lentink wasn't surprised at nature's superiority, he said that helicopter blades have come a long way. “The technology is at the level of an average hummingbird,” he said. “A helicopter is really the most efficient hovering device that we can build. The best hummingbirds are still better, but I think it's amazing that we're getting closer. It's not easy to match their performance, but if we build better wings with better shapes, we might match hummingbirds.”

    Professor Lentink said that we don't know how hummingbirds maintain their flight in a strong wind, how they navigate(确定方向) through branches, or how they change direction so quickly. He thinks that great steps could be made by studying wing aspect ratios-the ratio of wing length to wing width. Understanding these abilities and characteristics could be a benefit for robotics and will be the focus of future experiments.

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    There are 5.25 trillion pieces of plastic trash in the world's oceans, and each year, 8 million tons of plastic are added to the figure. Though the oceans seem vast enough to stomach a lot of plastic, the level of waste is starting to reach a crisis point: According to a new report by the Ocean Conservancy, by 2025, the ocean could contain one ton of plastic for every three tons of finfish.

All these floating bits of plastic not only disrupt marine ecosystems, but they also poison the global supply of seafood. “It's reaching crisis proportions,” says Andreas Merkl, CEO of the Ocean Conservancy. “Plastic breaks down into small pieces that look like plankton and is eaten by everyone from plankton to whales.” Plastic acts as a pollution sponge in the ocean, so when wildlife swallow pieces, the plastic might as well be a poison pill.

    The new report calls for a focus on improving waste management systems in a handful of developing countries that are most responsible for the plastic leakage into the ocean. China, Indonesia, the Philippines, Thailand and Vietnam contribute more than half of the oceans' plastic since their waste facilities hasn't kept up with rapid industrialization.

    On average, only about 40% of waste in these countries is actually picked up for disposal. But it's not just uncollected waste floating around-though that is three-fourths of the problem. The other quarter of the oceans' plastic came from post-collection activities. Even when a waste management company picks up waste to landfill it, poorly equipped landfills or illegal dumping mean that trash still ends up in the ocean.

    But how can countries stop the leakage of waste into the ocean? The Ocean Conservancy report suggests five “levers”: waste collection services, closing the leakage points within the collection system, gasification and burning of waste, and recycling facilities. The average waste ends up as litter. Just by expanding collection systems and plugging up their leakage points, the report says plastics leakage could by cut by 50% by 2020.

    It's not just an environmentalist's daydream. Coca-Cola and Dow Chemical, along with some other multinational companies have joined forces with Ocean Conservancy to fight ocean pollution. “We're committed to working toward a future of a plastic-free ocean. Companies don't make plastic with the intent of it ending up in the ocean, and we acknowledge the strong role industry must play in order to help eliminate ocean plastic waste by 2035.” Says Dow Packaging and Speciality Plastics' global sustainability director in a press release.

    Merkl emphasized that the countries can't recycle their way out of the problem. Only about 20% of the waste is valuable enough to be worth recycling: the rest, needs to be sent to sanitary landfills or waste-to-energy plants. “You have to concentrate on the fundamentals of waste management,” he says. And while building landfills and incinerators(焚化炉)across these developing countries might not be pretty, it's far more environmentally friendly than letting waste slide into the world's oceans.

    Some students prefer a part­time job after class to earn some money and improve their working and communication abilities. Here are some good companies for you to choose.

    In­N­Out Burger

    It's the best hamburger shop in the west of America. Thought as one of the best employers, it offers flexible working hours and the highest starting part­time salaries (薪水). Above all, the company treats its workers the way they would like to be treated: like family.

    Position: selling assistant (experience required)

    Website：www.in­n­out.com

    Starbucks Coffee

    Starbucks has been a leader of the United States' coffee. Working hours are flexible. There is also a 30% discount and a free pound of coffee or box of tea every week.

    Position: coffee waiter (experience required)

    Website: www.starbucks.com

    Whole Foods Market

    Whole Foods Market is the world's largest natural and organic food selling company. With its focus on organic food, Whole Foods Market is all about health. Working hours are not fixed. You can get a 20% discount. There are also training courses on health and food every week.

    Position: secretary

    Website: www.wholefoodsmarket.com

    Lands' End

    Lands' End is a Wisconsin­based clothing retailer(零售商). Working hours can be changed easily to suit any new situation. Workers (even part­time workers) have the chance to go to a company­owned centre and get a 25% discount, and an invitation to the yearly company picnic.

    Position: salesman

    Website: www.landsend.com

B

    In the 1760s, Mathurin Roze opened a series of shops that boasted(享有）a special meat soup called consomme. Although the main attraction was the soup, Roze's chain shops also set a new standard for dining out, which helped to establish Roze as the inventor of the modern restaurant.

    Today, scholars have generated large amounts of instructive research about restaurants. Take visual hints that influence what we eat: diners served themselves about 20 percent more pasta(意大利面食）when their plates matched their food.  When a dark-colored cake was served on a black plate rather than a white one, customers recognized it as sweeter and more tasty.

    Lighting matters, too. When Berlin restaurant customers ate in darkness, they couldn't tell how much they'd had: those given extra-large shares ate more than everyone else, but were none the wiser—they didn't feel fuller, and they were just as ready for dessert.

    Time is money, but that principle means different things for different types of restaurants. Unlike fast-food places, fine dining shops prefer customers to stay longer and spend. One way to encourage customers to stay and order that extra round: put on some Mozart(莫扎特）.When classical, rather than pop, music was playing, diners spent more. Fast music hurried diners out. Particular scents also have an effect: diners who got the scent of lavender(薰衣草）stayed longer and spent more than those who smelled lemon, or no scent.

    Meanwhile, things that you might expect to discourage spending—"bad" tables, crowding, high prices — don't necessarily. Diners at bad tables — next to the kitchen door, say — spent nearly as much as others but soon fled. It can be concluded that restaurant keepers need not "be overly concerned about 'bad' tables," given that they're profitable. As for crowds, a Hong Kong study found that they increased a restaurant's reputation, suggesting great food at fair prices. And doubling a buffet's price led customers to say that its pizza was 11 percent tastier.

    Why do people lie? Many psychologists agree that it can start from childhood? There are various reasons why children make false statements. They usually tell untruthful stories to cover up the mistakes that they have done in the past. Lying is also a way to avoid receiving punishments from parents. If parents fail to reprimand their children for making up false stories, then there is a possibility that they will continue to lie during their teenage years.

    Teenagers lie because they want to be accepted by their friends. This is the main reason why they create stories that are not true just to become presentable and acceptable to other people. In some instances, teenagers tell untruthful statements to avoid criticisms from their families and friends.

    As teenagers grow, lying becomes one of your habits. Their knowledge on making up untruthful stories becomes more developed. People lie in workplaces if they fail to meet the deadlines and if they fail to accomplish and do their tasks efficiently. Some of the common lies made in workplaces are getting sick and having emergencies at home. The danger involved in frequent lying is when it, becomes a character. Frequent lying causes the development of the condition known to doctors as pathological（病态的）lying.

    Pathological lying is a mental health condition, which is associated with individuals who have the urge to tell untruthful statements. Patients suffering from it make up stories about everything and anything. These individuals lie to meet the standards of other people who they want to please. These patients deceive other people because it gives them an unexplained pleasure. One of the best ways of treating pathological liar is to help them tell true statements and stories at all times. This may be hard for them, but as they are accustomed to it, they will start to realize that they will be more accepted by their families and other people if they stop themselves from making up for stories

    The American dream is the faith held by many people in the United States of America that through hard work, courage, creativity and determination, they can achieve a better life for themselves. More specifically, they agree on how to get ahead in America: get a college education, find a reliable job, and buy their own house. But do Americans still believe in that path, and if they do, is it attainable?

    The most recent National Journal poll(民意测验，投票) asked participants about the American dream, what it takes to achieve their goal, and whether or not they felt the control over their ability to be successful. Obviously, the results show that today, the idea of the American dream and what it takes to achieve it looks quite different from it did in the late 20th century. By the large, people felt that their actions and hard work — not outside forces — were the deciding factors in how their lives turned out. But the participants had definitely mixed feelings about what actions make for a better life in the current economy.

    In the last seven years, Americans have grown more pessimistic about the power of education to lead to success. Even though they see going to college as a fairly achievable goal, a majority 52 percent think that young people do not need a 4-year college education in order to be successful.

    Miguel Maeda, 42, who has a master's degree and works in public health, was the first in his family to go to college, which has allowed him to achieve a sense of financial stability(稳定) his parents and grandparents never did. While some, like Maeda, emphasized the value of a degree rather than the education itself, others still see college as a way to gain new viewpoints and life experiences. Sixty-year-old Will Fendley, who had a successful career in the military and never earned a college degree, think “personal drive” is far more important than just go to college. To Fendley, a sense of drive and purpose, as well as an effective high-school education, and basic life skills, like balancing a checkbook(支票簿), are the necessary elements for a successful life in America.