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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    It's such a happy-looking library, painted yellow, decorated with palm-tree stickers and sheltered from the Florida sun by its own roof. About the size of a microwave oven, it's pedestrian-friendly, too, waiting for book lovers next to a sidewalk in Palm Beach country Estates, along the northern boundary of Palm Beach Gardens.

    It's a library built with love.

  A year ago, shortly after Janey Henriksen saw a Brian Williams report about the Little Free Library organization, a Wisconsin-based nonprofit that aims to promote literacy and build a sense of community in a neighborhood by making books freely available, she announced to her family of four, “That's what we're going to do for our spring break!”

    Son Austin, now a 10th-grader, didn't see the point of building a library that resembles a mailbox. But Janey insisted, and husband Peter unwillingly got to work. The 51-year-old owner of a ship supply company modified a small wooden house that he'd built years earlier for daughter Abbie's toy horses, and made a door of glass.

    After adding the library's final touches (装点), the family hung a signboard on the front, instructing users to “take a book, return a book,” and making the Henriksen library, now one of several hundred like it nationwide and among more than 2,500 in the world, the only Little Free Library in Palm Beach County.

    They stocked it with 20 or so books they'd already read, a mix of science fiction, reference titles, novels and kids' favorites. “I told them, keep in mind that you might not see it again,” said Janey, a stay-at-home mom.

    Since then, the collection keeps replenishing (补充) itself, thanks to ongoing donations from borrowers. The library now gets an average of five visits a day.

    The project's best payoff, says Peter, are the thank-you notes left behind. “We had no idea in the beginning that it would be so popular.”  (317 words)

I really love this saying, "Love is endless and unlimited." For me, there's a story behind it. When I used to hand out chocolates with beautiful paper bags, my friends always told me, "You are wasting time and money. No one here believes in nameless gifts." To be honest, I have noticed that people here do donate (捐赠)in temples. They give food to the poor, and provide clothes and other things for whoever is in need.

    I think maybe I am the one who starts to think of the dogs in our neighborhood. When I moved into this new community, I noticed that there were two street dogs. They were wounded and homeless, and everyone used to stay away from them and hit them when they came any closer. They were becoming thinner and thinner and they would did of hunger sooner or later.

    But my habit of loving dogs has changed all these things. I began to walk close to them and give them food regularly. When I touched their heads and gave love to them, I could see tears in their eyes. My friends noticed, and now even kids and elders in the community provide them with food and also love them. I am really glad to see that I saved their lives.

    What I started will lead to beautiful memories with them. They enjoy playing with me and they even have a particular pose when they see me. I see a sparkle in their eyes and a smile on their faces. They are priceless for me.

    Amazing concept images have shown what homes of the future could look like, as preparations are made for the world's first free from 3D-printed property (房产).

    Experts will build a house called Curve Appeal, which will be 3D-printed off-site before being put together on-site to create two outside walls, a roof and an inside part. These four main sections will then be joined together.

    Although 3D-printed buildings have been made before, this home - to be constructed in Chattanooga, Tennessee, later this year — will be the first of its kind, as it will contain no regular shapes or angles. The house is the creation of the design company WATG, based in London and California. The design for Curve Appeal draws inspiration from the Case Study House program.

    The architects leading the program were famed for constantly pushing the limits in terms of minimalist (极简主义) materials, and trying to create open-plan spaces that focused on enhancing (增强) natural light. In a written statement, a spokesman for WATG said, “Employing many of the same modem design principles, Curve Appeal is the next evolutionary step. It's important that the architecture and the environment work together harmoniously. The chosen site is steps away from the Tennessee River in a beautiful wooded, sunlit area.”

    WATG was awarded the first prize in the Freeform Home Design Challenge in 2016 and given prize money of $ 8,000 to make its plans a reality. The competition was aimed at architects, designers, engineers and artists. Participants were challenged to design a 600 to 800sq ft single-family home that rethinks traditional aesthetics (美学), ergonomics, construction, building systems and structure.

    Over the last year, WATG's Chicago office has been developing their design with Branch Technology. This project is currently underway, working towards breaking ground later this year. Once completed, the Curve Appeal home will have open and light-filled inside living spaces.

    Developing healthy eating habits starts from childhood, therefore it is important for parents to teach and provide children with a healthy diet. DPHSS administrator of the Bureau of Nutrition Services, Charlie Morris told KUAM News, "A healthy diet for a child consists of a lot of fruits and vegetables in the diet limiting the amount of simple sugars in the diet and high fat food and highly processed(加工的) food."

    This means staying away as much as possible from food such as chips, cookies, candies and sugary drinks, as all children need to have meals which involve a well-balanced diet. Community nutritionist(营养学家) Thelma Romoso said, "The fruit, the vegetable, the grain, the protein, and also the milk, the diary product, so for the fruits it's easy for a mother to go into the two plus three concept of fruits and vegetables or five a day."

    This concept means that there are at least two servings of fruits a day, three servings of vegetables a day which can be served for lunch and dinner. As for protein parents can make a variety of dishes from chicken, beef, fish or even dried beans to make sure the child gets three servings a day.

    Morris said that the child's hunger level controls how much is eaten and the parent controls what and when the meal is offered, saying, "Mom needs to ensure that the food offered is good food for the child to eat and throughout the day depending on how active they are, snacks(零食) are not a bad thing, so the mom should offer good kinds of snacks."

    When it comes to preparing your child's lunch and snacks for school, make sure to keep in mind that the food you provide should not only be a source of energy but also be nutritionally beneficial such as fresh fruits, and whole grain bread. But parents must be sure to remember that a good nutritional diet must be balanced with physical activity, namely it is important that children get outside and run around and play and get activity in addition to eating a good diet.

    Did you know that Albert Einstein could not speak until he was four years old, and did not read until he was seven? His parents and teachers worried about his rnental ability.

    Beethoven's music teacher said about him，"As a composer（作曲家）he is hopeless." What if this young boy believed it?

    When Thomas Edison was a young boy, his teachers said he was so stupid that he could never learn anything. He once said, I remember I used to never be able to get along at school. I was always at the foot of my class…My father thought I was stupid, and I almost decided that l was a stupid person. "What if young Thomas believed what may said about him?

    When the sculptor(雕刻家)Auguste Rodin was young; he had difficulty learning to read and write. Today, we may say he had a learning disability. His father said of him, "I have an idiot(白痴) for a son." His uncle agreed. "He's uneducable," he said. What if Rodin had doubted his ability?

    Walt Disney was once fired by a newspaper editor because he was thought to have no "good ideas". Enrico Caruso was told by one music teacher, "you can't sing. You have no voice at all." And an editor told Louisa May Alcott that she was unable to write anything that would have popular appeal.

    What if these people had listened and become discouraged? Where would our world be without the music of Beethoven, the art of Rodin or the ideas of Albert Einstein and Walt Disney? As Oscar Levant once said, "It's not what you are but what you don't become that hurts."

    You have great potential. When you believe in all you can be, rather than all you cannot become, you will find your place on earth.