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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    People who have lost the ability to understand or use words due to brain damage are called aphasics（失语症患者）.Such patients can be extremely good at something else.From the changing expressions on speakers' faces and the tones of their voices,they can tell lies from truths.

    Doctors studying the human brain have given a number of examples of this amazing power of aphasics.Some have even compared this power to that of a dog with an ability to find out the drugs hidden in the baggage.

    Recently,scientists carried out tests to see if all that was said about aphasics was true.They studied a mixed group of people.Some were normal;others were aphasics.It was proved that the aphasics were far ahead of the normal people in recognizing false speeches—in most cases,the normal people were fooled by words,but the aphasics were not.

    Some years ago,Dr.Oliver Sacks wrote in his book about his experiences with aphasics.He mentioned a particular case in a hospital.Some aphasics were watching the president giving a speech on TV.Since the president had been an actor earlier,making a good speech was no problem for him.He was trying to put his feelings into every word of his speech.

    But his way of speaking had the opposite effect on the patients.They didn't seem to believe him.Instead,they burst into laughter.The aphasics knew that the president did not mean a word of what he was saying.He was lying!

    Many doctors see aphasics as people who are not completely normal because they lack the ability to understand words.However,according to Dr.Sacks,they are more gifted than normal people.Normal people may get carried away by words.Aphasics seem to understand human expressions better,though they cannot understand words.

    Many years later, when people recall the 2018 Russia World Cup, they will remember many things. With the tragic ending of the defending champion Germany, Mexico has triumphantly and suddenly lost three goals in the face of Sweden. But people will never forget the back of a lonely person. That is Lionel Messi.

    31-year-old Messi took off the green armband of his left arm and suddenly fell out. In the recent match, he and his team lost the game against France. The 19-year-old striker Mbappé relentlessly ripped apart the Argentine defense line and scored twice, which made a great contribution to the victory of France.

    On this planet, anyone who knows a little about football knows the name Lionel Messi and his golden years from 2007 to 2017.

    In 2007, 19-year-old Messi tied Real Madrid three times with a hat-trick, and began his legendary career.

    In the past ten years, Mr. Football, the Golden Globe Award and the Golden Boot Award have been taken over by him.

    He led Argentina and Barcelona to make a name for themselves in the world, and has a brilliant record in the Champions League, America's Cup and World Cup.

    Eleven years later, Messi stood on the Kazan Stadium. After four World Cups, he knew that this might be the last time he led Argentina to the World Cup.

    Since 1986, Argentina has never won a championship again. As a captain, he has a great responsibility, even stating that he would withdraw from the national team if he did not win the championship this year.

    This is a prophecy.

    Messi, who eventually failed to save the game, did not receive any interview after standing up on the lawn; leave behind only a legendary image for the world.

    The summer holidays are coming up. It's time to fill the bookshelves with quality literature for the kids. Here are some great books.

    Josephine Wants to Dance by Jackie French

    Price: $14.99 (for ages 4+)

    Josephine is a kangaroo who loves to dance. Her little brother, Joey, tells her that kangaroos don't dance; they jump. But Josephine continues to point her toes and leap through the air. When a ballet group comes to town and the lead ballerina (芭蕾舞演员) is injured, Josephine is called upon to help save the day. Can she do it, and, more importantly, does it matter that she's a kangaroo?

    House of Secrets by Chris Columbus

    Price: $19.99 (for ages 9+)

    The Walker kids —Caroline, Brendan and Nell—may have saved the world, but they can't save their home and must leave Kristoff House. Things can't get any worse, but then it turns out that the Wind Witch is still alive and planning an attack. To defeat her, the Walkers must return to the book world. The Walkers always help each other, but they must do it alone in their most important mission yet. And this time, if they fail, there's no chance of coming back.

    Edge of Extinction Book 1 by Laura Martin

    Price: $16.00 (for ages 9+)

    If you like The Land of the Dinosaurs, you will love this book. Two hundred years ago, the first dinosaur was successfully cloned (克隆). Soon after, humans realized they'd made a big mistake. Thirteen-year-old Sky Mundy's father suddenly disappeared five years ago. Along with her best friend， Shawn， she steps out into the world above --a world of dinosaurs --to look for him. Then she learns that everything she's been taught has been a lie.

Three magical destinations just one day!

    TOUR DETAILS

    Windsor Castle

    Time-honored in history, Windsor Castle is proudly located on a wooded hill overlooking the Thames River. Dating back to Norman times, it is famous for sweeping landscaped gardens, which is easy to see why it's the Queen's favorite week place. Famous for its architecture and Royal palace, the Castle was built in the 11th century after the Norman invasion. It's home to priceless artworks and you can visit Queen Mary's Dolls' House. Remember don't miss the ceremony—Changing of the Guards.

    Stonehenge

    Stonehenge is located in the county of Wiltshire. This is your chance to see a side of the world-famous stones that most people don't get a chance to see! You will never forget your first glimpse of grand Stonehenge with its rocks rising up against the skyline on Salisbury Plain. There are many unsolved mysteries about the rocks. Was Stonehenge intended as a religious temple? A clock for astronomy? A burial ground? Make up your own mind as you explore this unique site that has confused the world for 5, 000 years.

    Bath

    Beautiful Bath was the first city in England to be added to the UNESCO World Heritage List. No tour of Bath would be complete with a visit to the famous Roman Baths that gave the city its name. This beautifully preserved bathing site still has flowing water from Brain's only hot spring. You will be amazed by the impressive torch-lighting ceremony as dusk falls. You can also have a taste of Bath's water in Pump Room, where hot waters are drawn for drinking.

    British Museum Visitor Regulations

    Opening hours

    We open the Museum's galleries daily from 10：00 am until 17：30 pm. We keep selected galleries open until 20：30 pm on Fridays.

    The Museum's Great Court is open from 9:00 am until 18:00 pm; except on Fridays when it remains open until 20:30 pm.

    You may be asked by your staff to begin leaving up to ten minutes before closing time.

    The Museum is closed 24-26 December and 1 January.

    Admission

    We warmly welcome you on your visit to the Museum. In the interests of the security of all of our visitors we require you follow these regulations.

    Admission to the Museum is free, but we may charge for entry to some temporary exhibitions and events.

    Food and drink

    You aren't allowed to consume food and drink inside the Museum, except in places such as the restaurant and cafes or the forecourt. Families with children may use the Ford Centre for young visitors in the basement of the Museum's Great Court at weekends and during school holidays.

    Animals

    If you have a disability, you may be accompanied in the Museum by your guide, assistant or companion animal. You aren't allowed to bring animals into the Museum under any other circumstance.

    Film, photography and audio recording

    Except the place that are indicated by notices, you're permitted to use hand-held cameras (including mobile phones) with flash bulbs or flash units, and audio and film recording equipment not requiring a stand. You may use your photographs, film and audio recordings only for your own private and non-commercial purposes.