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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In 1974, after filling out fifty applications, going through four interviews, and winning one offer, I took what I could get —- a teaching job at what I considered a distant wild area: western New Jersey. My characteristic optimism was alive only when I reminded myself that I would be doing what I had wanted to do since I was fourteen —— teaching English.

    School started, but I felt more and more as if I were in a foreign country. Was this rural area really New Jersey? My students took a week off when hunting season began. I was told they were also frequently absent in late October to help their fathers make hay on the farms. I was a young woman from New York City, who thought that “Make hay while the sun shines” just meant to have a good time.

But, still, I was teaching English. I worked hard, taking time off only to eat and sleep. And then there was my sixth-grade class — seventeen boys and five girls who were only six years younger than me. I had a problem long before I knew it. I was struggling in my work as a young idealistic teacher. I wanted to make literature come alive and to promote a love of the written word. The students wanted to throw spitballs and whisper dirty words in the back of the room.

    In college I had been taught that a successful educator should ignore bad behavior. So I did, confident that, as the textbook had said, the bad behavior would disappear as I gave my students positive attention. It sounds reasonable, but the text evidently ignored the fact that humans, particularly teenagers, rarely seems reasonable. By the time my boss, who was also my taskmaster, known to be the strictest, most demanding, most quick to fire inexperienced teachers, came into the classroom to observe me, the students exhibited very little good behavior to praise.

    My boss sat in the back of the room. The boys in the class were making animal noises, hitting each other while the girls filed their nails or read magazines. I just pretended it all wasn't happening, and went on lecturing and tried to ask some inspiring questions. My boss, sitting in the back of the classroom, seemed to be growing bigger and bigger. After twenty minutes he left, silently. Visions of unemployment marched before my eyes.

    I felt mildly victorious that I got through the rest of class without crying, but at my next free period I had to face him. I wondered if he would let me finish out the day. I walked to his office, took a deep breath, and opened the door.

He was sitting in his chair, and he looked at me long and hard. I said nothing. All I could think of was that I was not an English teacher; I had been lying to myself, pretending that everything was fine.

    When he spoke, he said simply, without accusation, “You had nothing to say to them.”

     “You had nothing to say to them”. he repeated.” No wonder they are bored. Why not get to the meat of literature and stop talking about symbolism. Talk with them, not at them. And more important, why do you ignore their bad behavior”? We talked. He named my problems and offered solutions. We role-played. He was the bad student, and I was the forceful, yet, warm, teacher. 
       As the year progressed, we spent many hours discussing literature and ideas about human beings and their motivations. He helped me identify my weaknesses and strengths. In short, he made a teacher of me by teaching me the reality of Emerson's words: “The secret to education lies in respecting the pupil.”

    Fifteen years later I still drive that same winding road to the same school. Thanks to the help I received that difficult first year, the school is my home now.

    When I told my father that I was moving to Des Moines, Iowa, he told me about the only time he had been there. It was in the 1930s, when he was an editor of the literary magazine of Southern Methodist University（SMU）in Dallas, Texas. He also worked as a professor at SMU, and there was a girl student in his class who suffered from a serious back disease. She couldn't afford the operation because her family was poor.

    Her mother ran a boardinghouse in Galveston, a seaside town near Houston, Texas. She was cleaning out the attic（阁楼）one day when she came across an old dusty manuscript（手稿）. On its top page were the words, “By O. Henry”. It was a nice story, and she sent it to her daughter at SMU, who showed it to my father. My father had never read the story before, but it sounded like O. Henry, and he knew that O. Henry had once lived in Houston. So it was possible that the famous author had gone to the beach and stayed in the Galveston boardinghouse, and had written the story there and left the manuscript behind by accident. My father visited an O. Henry expert at Columbia University in New York, whoauthenticatedthe story as O. Henry's.

My father then set out to sell it. Eventfully, he found himself in Des Moines, meeting with Gardner Cowles, a top editor at the Des Moines Register. Cowles loves the story and bought it on the spot. My father took the money to the girl. It was just enough for her to have the operation she so desperately needed.

My father never told me what the O. Henry story was about. But I doubt that it could have been better than his own story.

    For students at the Farm School in Hamilton, Virginia, the classroom is outside every day. Jaclyn Jenkins is the founder of the school. “The No. 1 question we get immediately from parents is 'What happens if it rains?' And we say, 'Bring an extra set of clothes!'” Jenkins adds, “We still educate them. Their brains are working when they're moving. So, our goal is to always be outside.” The Farm School is a preschool, a place for 3- and 4-year-olds to learn and play.

    Alison Huff has taught at other schools. She says the Farm School gives its students more of a hands-on learning experience. For example, children use pumpkins to learn about colors and counting. They learn about measurement by planting seeds 30 centimeters apart. Huff adds, “We can use everything a regular preschool uses, but out in the garden.” In addition to planting vegetables and fruits, children help prepare food and clean up afterwards. The school teaches the children to cook using the food they have grown. “They can see the benefits of what they have in the garden and taste it then instead of going to the grocery store and buying it,” says Huff.

    The preschoolers also learn words in languages other than English. Huff speaks in both English and Spanish. Her assistant speaks French and Arabic. A 3-year-old in her class speaks four different languages.

    Farm animals are also an important part of the education program. Jenkins says the children learn about a different animal every month. Two months ago, she says, that animal was a cow. “We do actually have a cow that we bring to the school. They get to see what the cow is like, an learn what cows eat. They use little gloves and pretend to actually milk a cow. They make butter and yogurt.” The children spent another month with a large bird — a turkey.

    The idea for a school like this started after Jenkins and her husband bought a farm in Hamilton, with a late 18th-century house. They called it “One Day Farm” because years earlier they had hoped that “one day” they would have a farm. “That's when it started, the spark of a farm school,” said Jenkins.

    If you are travelling in Britain, besides so many world-class things to see and do in London, planning a day trip away from it can also be good.

Stonehenge

    Stonehenge consists of a group of large standing stones. The 5,000-year-old stones are one of the world's biggest mysteries(谜) that no one has understood yet. While travelling Stonehenge, you can imagine wildly and decide for yourself how the stones came to be there and why. Although you can't touch the stones, you can walk among them and feel the changes of seasons.

Windsor

    Most people visit Windsor to see Windsor Castle, where the Queen spends most of her time. The castle(城堡) itself could keep you busy for days. The best way to appreciate Windsor Castle is to approach via the Long Walk, a straight road where there are no cars, but you might see some deer.

Oxford

    Oxford is best known for its world-famous university. The large student population keeps the university young and fresh, though there's no shortage of history if you want it. 30 colleges make up the university itself. A tour of the colleges is a must—Harry Potter fans will find many places used in the movies.

Bath

    Founded by the Romans, who used the area's springs to create a spa retreat（水疗中心）, Bath's now the best tourist attraction of Southwest England. Visitors never miss the Roman Bath Complex, which is divided into four main parts—the Bath House, the Sacred Spring, the Roman Temple and the museum, which displays fascinating finds from the historical ruins of the city.

    10-year-old Mikaila Ulmer from Texas is building a lemonade（柠檬水）empire, hoping to save honey bees in the process.

    It all started when Mikaila was 4 years old and she was bitten by a bee twice in one week. This caused her to become very scared whenever bees were near. In order to help her manage this new fear, Mikaila's parents asked her to do some research on bees. She learned that bees are quite important for flowers, gardens and trees. She also learned that they are dying at a rapid rate. In the past year, honeybee farmers have reported losing nearly 42% of them. Many believe that this could be due to the overuse of pesticides（杀虫剂）.

    This is when she set her mind to create a product to help save bees. She started her company BeeSweet Lemonade. Her special lemonade recipe came from her great-grandmother's cookbook. She adds honey to it, instead of sugar. In order to call attention to the problems honeybees face, Mikaila sells lemonade almost every day at her lemonade stand. And she takes every opportunity to tell her customers about the problems that face honeybees.

    What began as a small activity is starting to grow. BeeSweet is projected to sell almost 140,000 bottles of lemonade this year. BeeSweet lemonade can be found on the shelves at select Whole Foods Markets as well as many restaurants and other locations near her home.

    Does Mikaila have any time to just be a kid? Sure! Every weekend Mikaila does something fun. She doesn't mind the hard work though. She says that she is happy watching people enjoy her lemonade. The more people enjoy it, the more they're learning about the bees.