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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    A middle-aged man with a long beard was caught by the police for bad behavior and property damage. The man, Bill Wild, checked into a hotel last night, telling the clerk he would pay cash in advance and would be staying for four nights. He then asked her where the nearest store was and she told him it was John-Johns.

    Wild went to the store and bought three gallons of honey and four gallons of chocolate syrup (糖浆). The cashier asked him why he wanted these things and he replied, "I'm trying to become a sweeter person." The cashier smiled at the joke. Wild drove back to the hotel. He opened all bottles and poured them into the bathtub. He added warm water to the mix. He tuned the radio to an opera music station, took off his clothes, jumped into the tub, and started singing loudly with the music.

    Fifteen minutes later, the neighbor phoned the clerk complaining about the noise. The clerk knocked on Wild's door, but he just kept singing. She phoned his room, but he didn't answer. Then she called the police, who arrived quickly. They broke into the room. The floor was covered in water and the bathtub was full of chocolate and honey. "He seemed so nice and friendly. Who'd have thought he was a bathtub-singing nut?" said the clerk. The police said this was the third time that Wild had been arrested for this kind of behavior.

    One second-grade student wanted to help erase school lunch debt for her fellow students, so she decided to create lemonade stands to raise funds（资金）.

    Amiah Van Hill was inspired to raise funds to help pay off her classmates' lunch debt back in May after reading about Jeffery Lew. The father of three crowd-funded to cover the cost of unpaid lunches in the Seattle School District, where his 8-year-old son took part. “She's a really strong reader, so she read the story and said, 'Wow, this is great! I wonder if there's any kids at my school that need help paying their lunches,'” said her mother, Rachel Van Hill.

    Amiah, 6, and Aria, 4, discovered that at Hayden Meadows Elementary School in Idaho, the unpaid lunch debt was $40.55. They set up a lemonade stand last month to raise the money, with a sign reading, “Lemonade 4 Lunch.” During their first set-up, the two met their goal within an hour.

    The school was very much appreciative. Principal Lisa Pica said “Our school believes in giving back to the community and we are excited that Amiah has got that value at such a young age and we are so proud that she has found a way to help those in need. She is a very special little lady.”

    After discovering it was “easy” to pay off one school's debt, they set up another lemonade stand a week later to raise money for two more local schools. The girls then decided to set their sights higher and raise funds for the entire Coeur d'Alene Public School district. In 22 days, they've raised more than $2,700. The school district is excited to recognize her for her good deed.

    The medical world is gradually realizing that the quality of the environment in hospital may play an important role in helping patients to get better.

    As part of a nationwide effort in Britain to bring art out of the museums and into public places, some of the country's best artists have been called in to change older hospitals and to soften the hard edges of modern buildings. Of the 2500 national health service hospitals in Britain, almost 100 now have very valuable collections of present art in passages, waiting areas and treatment rooms.

    These recent movements first started by one artist, Peter Senior, who set up his studio at a Manchester hospital on northeastern England during the early 1970s. He felt the artist had lost his place in modern society, and that art should be enjoyed by a wider audience.

    A common hospital waiting room might have as many as 5,000 visitors each week. What a better place to hold regular exhibitions of art! Senior held the first exhibition of his own paintings in the outpatients waiting area of the Manchester Royal Hospital in 1975. Believed to be Britain's first hospital artist, Senior was so much in demand that he was soon joined by a team of six young art school graduates.

    The effect is striking. Now in the passages and waiting rooms the visitor experiences a full view of fresh colours, playful images and restful courtyards.

    The quality of the environment may reduce the need for expensive drugs when a patient is recovering from an illness. A study has shown that patients who had a view onto garden needed half the number of strong pain killers compared with patients who had no view at all or only a brick wall to look at.

    Since many of you are planning to study at a college or university in the future, you may be curious to know what your future study will be like. This is the question I want to discuss with you today.

    First, let's talk about what your weekly timetable will look like. No matter what your major may be, you can expect to spend between four and six hours a week for each class attending lecture. Lectures are usually in very large rooms because some courses such as Introduction to Sociology or Economics often have as many as two or three hundred students, especially at large universities. In lectures, it's very important for you to take notes on what the professor says because the information in a lecture is often different from that in your textbooks. Also, you can expect to have exam questions based on the lectures. So it isn't enough to just read your textbooks; you have to attend lectures as well. In a typical week, you will also have a couple of hours of discussion for every class you take. The discussion part is a small group meeting usually with fewer than thirty students where you can ask questions about the lectures, the reading, and the homework. In large universities, graduate students called teaching assistants, usually direct discussion parts

    If your major is chemistry, or physics, or another science, you'll also have to spend several hours a week in the lab doing experiments. This means that science majors spend more time in the classroom than non-science majors do. On the other hand, people who major in subjects like literature or history usually have to read and write more than science majors do.

    The Gold Coast family holidays are always great fun whether you are from Australia or from abroad. There are beautiful beaches, adventure (冒险) parks, nature parks and so much more.

    There are so many sights to see here. It is a pity to drive in a car and you'll miss a great part of it. Australia is home to many animals and birds that can only be seen when moving slowly and going into the areas where they live.

    When you are on a bicycle, you have the advantage of being able to stop whenever you want to see an interesting animal or bird that you have never seen before. It is a quieter way of transportation as well, so you might even be able to take a picture. When you are on the beach, you can breathe that clean air and view the beauty of the water and sand. It is a totally different experience from passing it in a car.

    There are many choices of hiring (租用) a bicycle to experience the Gold Coast. There are stores that will fit a bike perfectly to your size. These bikes for both adults and children are in many kinds and colors to please any taste. If you have ever wanted to try a tandem bike (双人单车), now is your chance, because they have those too.

    A bicycle hire on Gold Coast is something that everyone should try at least once. This is a wonderful chance for anyone who likes to cycle and it is also a cheap way to travel with your family.