One day, Mr. Arnold was teaching a lesson, and things were going as normally as ever. He was explaining the story of human being to his pupils. He told them that, in the beginning, men were nomads (游牧); they never stayed in the same place for very long. Instead, they would travel about, here and there, in search of food, wherever it was to be found. And when the food ran out, they would move off somewhere else.

    He taught them about the invention of farming and keeping animals. This was an important discovery, because by learning to cultivate (耕作) the land, and care for animals, mankind would always have food steadily. It also meant that people could remain living in one place, and this made it easier to set about tasks that would take a long while to finish, like building towns, cities, and all that were in them. All the children were listening attracted by this story, until Lucy jumped up:

    “And if that was so important and improved everything so much, why are we nomads all over again, Mr. Arnold?”

    Mr. Arnold didn't know what to say. Lucy was a very clever girl. He knew that she lived with her parents in a house, so she must know that her family were not nomads; so what did she mean?

    “We have all become nomads again,” continued Lucy, “The other day, outside the city, they were cutting the forest down. A while ago a fisherman told me how they fish. It's the same with everyone: when there's no more forest left the foresters go elsewhere, and when the fish run out the fishermen move on. That's what the nomads did, isn't it?

    The teacher nodded, thoughtfully. Really, Lucy was right. Mankind had turned into nomads. Instead of looking after the land in a way that we could be sure it would keep supplying our needs, we kept developing it until the land was bare. And then off we would go to the next place! The class spent the rest of the afternoon talking about what they could do to show how to be more civilized (文明的).

    The next day everyone attended class wearing a green T-shirt, with a message that said “I am not a nomad!”

    And, from then on, they set about showing that indeed they were not. Every time they knew they needed something, they made sure that they would get it using care and control. If they needed wood or paper, they would make sure that they got the recycled kind. They ordered their fish from fish farms, making sure that the fish they received were not too young and too small. They only used animals that were well cared for, and brought up on farms.

    And so, from their little town, those children managed to give up being nomads again, just as prehistoric men had done, so many thousands of years ago.

    We all know the names of certain famous male inventors throughout history, from Galileo to Alexander Graham Bell to Steve Jobs. Do you know the outstanding ladies listed below?

    Margaret Knight (1838-1914)

    Margaret Knight was nicknamed “the lady Edison'' for her productive inventions which included a safety device for textile looms, shoe manufacturing machines, a rotary engine and internal combustion engine (内燃机), among many others. Knight received 27 patents in her lifetime.

    Josephine Cochran(1839-1913)

    Cochrane, a wealthy woman who entertained often, wanted a machine that could wash dishes faster than her servants, and without breaking them. When she couldn't find one, she built the first dishwasher herself in 1886. She received a patent for her famous invention and started a company to sell her invention to restaurants and hotels.

    Katharine Burr Blodgett (1898-1979)

    Katharine Blodgett was the first woman to receive a Ph.D in physics at England's Cambridge University and the first woman hired by General Electric. Her most influential invention was non-reflective glass, which today is still essential for eyeglasses, car windshields and computer screens.

    Stephanie Kwolek (1923-2014)

    In 1965, Stephanie Kwolek created an unusually lightweight and durable new fiber which was later developed by a chemical company DuPont into the synthetic Kevlar (凯夫拉尔纤维), used in everything from military helmets and bulletproof vests to work-gloves, sports equipment, and building materials. Kwolek was awarded the National Medal of Technology for her research on synthetic fibers and was admitted into the National Inventors Hall of Fame in 1994.

    I was in a terrible mood. Two of my friends had gone to the movies the night before and hadn't invited me. I was in my room thinking of ways to make them sorry when my father came in.

    "Want to go for a ride, today, Beck? It's a beautiful day."

    "No! Leave me alone!" Those were the last words I said to him that morning. My friends called and invited me to go to the mall with them a few hours later. I forgot to be mad at them and when I came home to find a note on the table. My mother put it where I would be sure to see it.

    "Dad has had an accident. Please meet us at Highland Park Hospital".

    When I reached the hospital, my mother came out and told me my father's injuries were extensive. "Your father told the driver to leave him alone and just call 911, thank God! If he had moved Daddy, there's no telling what might have happened. A broken rib（肋骨）might have pierced（穿透）a lung..."

    My mother may have said more, but I didn't hear. I didn't hear anything except those terrible words: Leave me alone. My dad said them to save himself from being hurt more. How much had I hurt him when I hurled those words at him earlier in the day?

    It was several days later that he was finally able to have a conversation. I held his hand gently, afraid of hurting him.

    "Daddy… I am so sorry…"

    "It's okay, sweetheart. I'll be okay. "

    "No," I said, "I mean about what I said to you that day. You know, that morning?"

My father could no more tell a lie than he could fly. He looked at me and said. "Sweetheart, I don't remember anything about that day, not before, during or after the accident. But I remember kissing you goodnight the night before. "He managed a weak smile.

    My English teacher once told me that words have immeasurable power. They can hurt or they can heal. And we all have the power to choose our words. I intend to do that very carefully from now on.

    Getting stuck in a traffic jam is one of the most boring problems for people living in big cities. The fact that you're moving so slowly leads too stress, anger and the wish that your car could just fly over the traffic like an airplane.

    Soon, however, that wish could come true .On May 8, US car-renting company Uber showed off what it described as "the transportation mode of the future: on-demand air transport," reported ABC News.

    According to Nikhill Goel, head of products for Uber Air, the company's air taxi service may launch test flights in the US cities of Dallas and Los Angeles, as well as Dubai in the United Arab Emirates, as early as 2020. If everything goes according to plan, passengers will be able to fly to work by 2023.

    When the Olympics comes to Los Angeles in 2028. Uber "expects to have hundreds, if not thousands, of its aircraft in the skies." Goel told Newsweek.

    So what would Uber's flying vehicles be like?

    They are small, electric aircraft that take off and land vertically (垂直地) , and they give off zero emissions (排放) and are quiet enough to operate in cities .

    Just like an airplane, the vehicles will have fixed wings to help them glide. But while a helicopter has just one big fixed rotor (定量). Uber's vehicles will have multiple rotors , which will help increase fuel efficiency (效率) while reducing emissions and noise.

    Because of these fixed wines and multiple rotors. Uber's flying taxis "should be quieter and safer than a helicopter." reported ABC News.

    However, the service still has a long way to go before it's ready to accept passengers. For example, to avoid any potential accidents. Uber is working with NASA to study air traffic control problems associated with low-flying aircraft. But just as Dubai's Mayor Betty Price said in a news release. "This program is revolutionary and future -oriented (面向未来的)."

    More than two thirds of the world's polar bears will be wiped out by 2050, according to a shocking new study. By then, scientists say, global warming will have melted 42 percent of the Arctic sea ice. By 2100, only a very few of these important creatures will be left.

    The report has been produced by the US Geological Survey. The scientists have publicized their findings in the hope of influencing US Interior Secretary Dirk Kempthorne, who has been asked to put polar bears on the US endangered species list.

    Polar bears depend on floating sea ice as a platform for hunting seals, which are their main food. Without enough ice, polar bears would be forced to go onto the land, where they are poorly skilled hunters, and would be unlikely to adapt to the life on the land in time. Experts say few little bears would survive and the stress could make many females unable to get pregnant.

    The team of American and Canadian scientists spent six months studying bears, on the ground, from spotter planes and in the lab, using computer models. Some team members fear the result is even worse for the bears than what their report says. They say the Arctic is warming faster than anywhere in the world and much faster than their computer had been forecasting. Satellite observations have showed that the ice has decreased to an all­time low.

    However, not everyone in the scientific community believes that global warming is happening on such an alarming scale. Another investigation has found that polar bears are still being hunted by wealthy “sportsmen” who want their skins and heads. At least ten international companies offer bear­hunting trips.

    Science is finaly beginning to embrace animals who were, for a long time, considered second-class citizens.

    As Annie Potts of Canterbury University has noted, chickens distinguish among one hundred chicken faces and recognize familiar individuals even after months of separation. When given problems to solve, they reason: hens trained to pick colored buttons sometimes choose to give up an immediate food reward for a slightly later (and better) one. Healthy hens may aid friends, and mourn when those friend die.

    Pigs respond meaningful to human symbols. When a research team led by Candace Croney at Penn State University carried wooden blocks marked with X and O symbols around pigs, only the O carriers offered food to the animals. The pigs soon ignored the X carriers in favor of the O's. Then the team switched from real-life objects to T-shirts printed with X or O symbols. Still, the pigs walked only toward the O-shirted people: they had transferred their knowledge to a two-dimensional format, a not inconsiderable feat of reasoning.

    I've been guilty of prejudiced expectations, myself. At the start of my career almost four decades ago, I was firmly convinced that monkeys and apes out-think and out-feel other animals. They're other primates(灵长目动物), after all, animals from our own mammalian(哺乳动物的) class. Fairly soon, I came to see that along with our closest living relatives, whales too are masters of cultural learning, and elephants express profound joy and mourning with their social companions. Long-term studies in the wild on these mammals helped to fuel a viewpoint shift in our society: the public no longer so easily accepts monkeys made to undergo painful procedure kin laboratories, elephants forced to perform in circuses, and dolphins kept in small tanks at theme parks.

    Over time, though, as I began to broaden out even further and explore the inner lives of fish, chickens, pigs, goats, and cows, I started to wonder: Will the new science of "food animals" bring an ethical (伦理的) revolution in terms of who we eat? In other words, will our ethics start to catch up with the development of our science?

    Animal activists are already there, of course, committed to not eating these animals. But what about the rest of us? Can paying attention to the thinking and feeling of these animals lead us to make changes in who we eat?