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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    An organization, Eye Care 4 Kids, is bringing much-needed eye care to poor kids. It provides free eye examinations for kids from poor families. Founded by Joseph Carbone in 2001, the organization has helped around 100,000 children in Utah and Nevada.

    Now, Cecil Swyers, a biomedical(生物医学的) engineer who was once a poor child himself, is bringing the charity's(慈善) services to poor students in Arizona, so that vision impairment(视力受损) doesn't stand in the way of their education.

    “Eye Care 4 Kids is bringing eye care and glasses to families that wouldn't have the means to pay for them,” said Mario Ventura from Isaac Elementary School District, the first school district in Arizona to receive its services.

    Good vision is important to a child's learning experience. According to a study, up to 80 percent of learning happens through sight for children between 6 and 18 years old. Without proper eye care, it's difficult for students to learn better and succeed.

    Swyers is hoping that by bringing the organization to Arizona he'll help a lot more students. He teamed up with two other organizations to get doctors to volunteer their time with the group. Using an Eye Care 4 Kids mobile clinic, Swyers visited Alta E. Butler Elementary School and has already helped 40 students.

    The school was grateful to receive the eye care, especially since the services came to them. “It's great for us,” said Assistant Principal Cindy Alonso.

    Swyers is hoping to bring Eye Care 4 Kids' services to other schools in the state. He said that hopefully his work will have a positive effect on students' futures. “If we can help students while they're young, we can make a difference in their futures,” he said.

    Closeness and independence are both important in our life. Though all humans need both of them, women tend to focus on the first and men on the second. It is as if their lifeblood ran in different directions.

    These differences can give women and men differing views of the same situation, as they did in the case of couple I will call Tracy and Brian. When Brian's old high school friend called him at work and announced he'd be in town on business the following month, Brian invited him to stay for the weekend. That evening he informed Tracy that they were going to have a houseguest, and that he and his friend would go out together the first night to chat like old times. Tracy was upset. She was going to be away on business the week before, and the Friday night when Brian would be out with his friend would be her first night home. But what upset her the most was that Brian had made these plans on his own and informed her of them, rather then discussing them with her before extending the invitation.

    Tracy would never make plans, for a weekend or an evening, without first checking with Brian. She can't understand why he doesn't show her the same courtesy and consideration that she shows him. But when she protests, Brian says, "I can't say to my friend, 'I have to ask my wife for permission'!"

    To Brian, checking with his wife means seeking permission, which implies that he is not independent, not free to act on his own. To Tracy, checking with her husband makes her feel good to know and show that she is involved with someone, that her life is bound up with someone else's.

    Tracy and Brian both felt upset by this incident because it cut to the core of their primary concerns. Tracy was hurt because she sensed a failure of closeness in their relationship: He didn't care about her as much as she cared about him. And he was hurt because he felt she was trying to control him and limit his freedom.

    We've all been there: in a lift, in line at the bank or on an airplane, surrounded by people who are, like us, deeply focused on their smartphones or, worse, struggling with the uncomfortable silence.

    What's the problem? It's possible that we all have compromised conversational intelligence. It's more likely that none of us start a conversation because it's awkward and challenging, or we think it's annoying and unnecessary. But the next time you find yourself among strangers, consider that small talk is worth the trouble. Experts say it's an invaluable social practice that results in big benefits.

    Dismissing small talk as unimportant is easy, but we can't forget that deep relationships wouldn't even exist if it weren't for casual conversation. Small talk is the grease(润滑剂) for social communication, says Bernardo Carducci, director of the Shyness Research Institute at Indiana University Southeast. "Almost every great love story and each big business deal begins with small talk," he explains. "The key to successful small talk is learning how to connect with others, not just communicate with them."

    In a 2014 study, Elizabeth Dunn, associate professor of psychology at UBC, invited people on their way into a coffee shop. One group was asked to seek out an interaction(互动) with its waiter; the other, to speak only when necessary. The results showed that those who chatted with their server reported significantly higher positive feelings and a better coffee shop experience. "It's not that talking to the waiter is better than talking to your husband," says Dunn. "But interactions with peripheral(边缘的) members of our social network matter for our well-being also."

    Dunn believes that people who reach out to strangers feel a significantly greater sense of belonging, a bond with others. Carducci believes developing such a sense of belonging starts with small talk. "Small talk is the basis of good manners," he says.

Darrion Cockrell,who wasn't much of a student,has been named Missouri's Teacher of the Year—the state's highest honor for educators,becoming the first male since 2015 to capture the state's top award.

Cockrell—the child of "a drug-addicted mother" and a father who was killed when he was four years old—was in and out of the childcare centers and eventually became a gang (帮派) member.In his speech,he shouted out the special people who helped to guide him down the right path when he was going off track.

He thanked his teacher Ken who provided him with life advice while he lived in a boys' group home."He taught me it's OK to be tough,but at the same time,it's OK to be compassionate (富有同情心的),"Cockrell said."He was like a father figure to me."

The teacher—affectionately known as "DC"—also expressed his gratitude to the football coach that adopted him when he was in the 7th grade and helped to change his whole perspective (视角) on life."When I changed the way I looked at things,the things around me started to change,"he said."I had a lot of struggles and a lot of hurdles,and if not for those educators,I would not be here today."

Now,Cockrell hopes to make an impact on the students at Lindbergh Schools' Crestwood Elementary in St.Louis,where he's been teaching physical education since 2015.Among his many accomplishments at the school is his development of the"Crest-Fit"training program for teachers,students and parents.

"Missouri is fortunate to have so many high-quality educators,and Darrion will be a wonderful representative as our state's Teacher of the Year,"Commissioner of Education Margie Vandeven said in a statement."He guides his students towards long-term physical and mental wellness,and the connections he has established will impact Crestwood children for years to come."

Spanish class scared me in the freshman year.I knew little Spanish before starting the class，and I thought it would be1 for me.However，Mary，our honored Spanish teacher，who was full of creativity，made her class fun from the beginning.I knew what to expect with a schedule for each week，but there was always some slight 2 . 

Before the exam，Mary often asked us to 3 our lessons by ourselves.But I could remember one day she said， "This time，let's play a game before going over what you've learned." The game was so interesting that we all 4 ourselves.After the exam，Mary gave us opportunities to make up for our 5 .After each error correction，she would check again.She took things so 6 that she wouldn't overlook any detail.No wonder she was 7 by us. 

Mary was 8 and willing to help，within reason，on everything.We could ask her questions at any time.She encouraged everyone to speak Spanish in class.Because of that，I was 9 enough，and then I could communicate with Spanish speakers outside of class.When she knew our problems，she would give advice.When someone was struggling，she would 10 . 

Mary's 11 teaching eventually transformed my 12 into fascination.She infused （灌输） foreign culture into lessons，using music and dance to 13 our language skills.Her personalized attention to each student's needs fostered a（n）14 environment.At the end of the term，my Spanish improved，and my confidence soared.Mary left a lasting impact on my 15 for new challenges.