2 . Can a small group of drones (无人机) guarantee the safety and reliability of railways and, at the same time, help railway operators save billions of euros each year? That is the very likely future of applying today’s “eyes in the sky” technology to make sure that the millions of kilometres of rail tracks and infrastructure (基础设施) worldwide are safe for trains on a 24/7 basis.

Drones are already being used to examine high-tension electrical lines. They could do precisely the same thing to inspect railway lines and other vital aspects of rail infrastructure such as the correct position of railway tracks and switching points. The more regularly they can be inspected, the more railway safety, reliability and on-time performance will be improved. Costs would be cut and operations would be more efficient (高效) across the board.

That includes huge savings in maintenance costs and better protection of railway personnel safety. It is calculated that European railways alone spend approximately 20 billion euros a year on maintenance, including sending maintenance staff, often at night, to inspect and repair the rail infrastructure. That can be dangerous work that could be avoided with drones assisting the crews’ efforts.

By using the latest technologies, drones could also start providing higher-value services for railways, detecting faults in the rail or switches, before they can cause any safety problems. To perform these tasks, drones for rail don’t need to be flying overhead. Engineers are now working on a new concept: the rail drones of the future. They will be moving on the track ahead of the train, and programmed to run autonomously. Very small drones with advanced sensors and AI and travelling ahead of the train could guide it like a co-pilot. With their ability to see ahead, they could signal any problem, so that fast-moving trains would be able to react in time.

4 . Race walking shares many fitness benefits with running, research shows, while most likely contributing to fewer injuries. It does, however, have its own problem.

Race walkers are conditioned athletes. The longest track and field event at the Summer Olympics is the 50-kilometer race walk, which is about five miles longer than the marathon. But the sport’s rules require that a race walker’s knees stay straight through most of the leg swing and one foot remain in contact (接触) with the ground at all times. It’s this strange form that makes race walking such an attractive activity, however, says Jaclyn Norberg, an assistant professor of exercise science at Salem State University in Salem, Mass.

Like running, race walking is physically demanding, she says, According to most calculations, race walkers moving at a pace of six miles per hour would burn about 800 calories(卡路里) per hour, which is approximately twice as many as they would burn walking, although fewer than running, which would probably burn about 1,000 or more calories per hour.

However, race walking does not pound the body as much as running does, Dr. Norberg says. According to her research, runners hit the ground with as much as four times their body weight per step, while race walkers, who do not leave the ground, create only about 1.4 times their body weight with each step.

As a result, she says, some of the injuries associated with running, such as runner’s knee, are uncommon among race walkers. But the sport’s strange form does place considerable stress on the ankles and hips, so people with a history of such injuries might want to be cautious in adopting the sport. In fact, anyone wishing to try race walking should probably first consult a coach or experienced racer to learn proper technique, she says. It takes some practice.

The Meredith family lived in a small community. As the economy was in decline, some people in the town had lost their jobs. Many of their families were struggling to make ends meet. People were trying to help each other meet the challenges.

Mrs. Meredith was a most kind and thoughtful woman. She spent a great deal of time visiting the poor. She knew they had problems, and they needed all kinds of help. When she had time, she would bring food and medicine to them.

One morning she told her children about a family she had visited the day before. There was a man sick in bed, his wife, who took care of him and could not go out to work, and their little boy. The little boy -his name was Bernard-had interested her very much.

“I wish you could see him,” she said to her own children, John, Harry, and Clara. “He is such a help to his mother. He wants very much to earn some money, but I don't see what he can do.”

After their mother left the room, the children sat thinking about Bernard. “I wish we could help him to earn money,” said Clara. “His family is suffering so much.”

“So do I,” said Harry. “We really should do something to assist them.”

For some moments, John said nothing, but, suddenly, he sprang to his feet and cried, “I have a great idea! I have a solution that we can all help accomplish(完成).”

The other children also jumped up all attention. When John had an idea, it was sure to be a good one. “I tell you what we can do,” said John. “You know that big box of corn Uncle John sent us? Well, we can make popcorn(爆米花), and put it into paper bags, and Bernard can take it around to the houses and sell it.”

6 . Some individuals are born with a gift for public speaking.    1    Do you want to be a good public speaker? Here are some principles you must master.

People want to listen to someone who is interesting, relaxed and comfortable. Too often when you stand up to give a speech, you focus on the “public”at the expense of the “speaking. ”       2     Focus on the speaking. Talk directly to your audience, be yourself and make a connection.

Even the most successful public speaker will make mistakes. Yet, the only one who cares about any mistake is the one who is speaking. People’s attention wanders constantly. In fact,most people only absorb about 20 percent of a speaker’s message. So, don’t stop speaking when you make a mistake unless it’s a truly serious one.    3    

Your goal is not to be a perfect public speaker.    4    And like everything else in life, that takes practice. Remember, even world champion athletes practice their skills on a consistent basis.

    5    It’s rare to hear someone say, “I wish that speaker had spoken longer. “On the other hand, you probably can’t count the times that you’ve thought, “I’m glad that talk is over. It seemed to go on forever! “So surprise your audience. Always make your presentation just a bit shorter than anticipated. It’s better to leave your listeners wishing for more than shifting restlessly in their seats waiting for your speech finally to end.

7 . We are the products of evolution, and not just evolution that occurred billions of years ago. As scientists look deeper into our genes (基因), they are finding examples of human evolution in just the past few thousand years. People in Ethiopian highlands have adapted to living at high altitudes. Cattle -raising people in East Africa and northern Europe have gained a mutation (突变) that helps them digest milk as adults.

On Thursday in an article published in Cell, a team of researchers reported a new kind of adaptation - not to air or to food, but to the ocean. A group of sea-dwelling people in Southeast Asia have evolved into better divers. The Bajau, as these people are known, number in the hundreds of thousands in Indonesia, Malaysia and the Philippines. They have traditionally lived on houseboats; in recent times, they’ve also built houses on stilts (支柱) in coastal waters. “They are simply a stranger to the land,” said Redney C. Jubilado, a University of Hawaii researcher who studies the Bajau.

Dr. Jubilado first met the Bajau while growing up on Samal Island in the Philippines. They made a living as divers, spearfishing or harvesting shellfish. “We were so amazed that they could stay underwater much longer than us local islanders,” Dr. Jubilado said. “I could see them actually walking under the sea.”

In2015, Melissa Ilardo, then a graduate student in genetics at the University of Copenhagen, heard about the Bajau. She wondered if centuries of diving could have led to the evolution of physical characteristics that made the task easier for them. “it seemed like the perfect chance for natural selection to act on a population,” said Dr. Ilardo. She also said there were likely a number of other genes that help the Bajau dive.

A Beautiful Place in China

9 . Languages have been coming and going for thousands of years, but in recent times there has been less coming and a lot more going. When the world was still populated by hunter-gatherers, small, tightly knit(联系) groups developed their own patterns of speech independent of each other. Some language experts believe that 10,000 years ago, when the world had just five to ten million people, they spoke perhaps 12,000 languages between them.

Soon afterwards, many of those people started settling down to become farmers, and their languages too became more settled and fewer in number. In recent centuries, trade, industrialization, the development of the nation-state and the spread of universal compulsory education, especially globalisation and better communications in the past few decades, all have caused many languages to disappear, and dominant languages such as English, Spanish and Chinese are increasingly taking over.

At present, the world has about 6,800 languages. The distribution of these languages is hugely uneven. The general rule is that mild zones have relatively few languages. Often spoken by many people while hot, wet zones have lots, often spoken by small numbers. Europe has only around 200 Languages: the Americas about 1,000, Africa 2,400; and Asia and the Pacific perhaps 3,200, of which Papua New Guinea alone accounts for well over 800. The median number(中位数) of speakers is a mere 6，000, which means that half the worlds languages are spoken by fewer people than that.

Already well over 400 of the total of 6,800 languages are close to extinction(消亡), with only a few elderly speakers left. Pick, at random, Busuu in Cameroon (eight remaining speakers), Chiapaneco in Mexico(150). Lipan Apache in the United States(two or three) or Wadjigu in Australia (one, with a question-mark): none of these seems to have much chance of survival.