With my hands and knees on the floor of the airplane, I was searching for an old lady's missing hearing aid during the flight from Sydney to Los Angeles. It occurred to me that this may not be the most dignified posture for a Buddhist nun(尼姑).

    I had seen the old lady from the seat in front of me as she walked up and down the passage with a flashlight. I asked a few times what was wrong, but she didn't answer at first —– she couldn't hear me. She was wearing a woolen coat. Judging from her accent, she came from Eastern Europe.

    Do you know how much hearing aids cost? Thousands, especially for the new tiny hidden-in-the-ear type she described. It takes a long time for an appointment to make a new one, and many doctor visits to get the thing adjusted right. Therefore, my dignity seemed less important than finding that hearing aid. But how does one find a tiny black object in a shadowy jet cabin（机舱）

    The lady wasn't even sure where or when she had lost it. At one point, a couple of flight attendants did a random search around the lady's seat; I wasn't impressed. They left suggesting that she search the seat of her previous flight! My flashlight turned up all kinds of small objects, bits of plastic, broken pieces of headphones.

    The old lady said that she gave up. Yet I couldn't. After we landed, as passengers streamed past us, I insisted that the lady move aside while awaiting her wheelchair. Then I got into a real down and dirty search among the dust under her seat and on the floor.

    Look! A little peanut-sized shiny black object caught the light of my flashlight in a floor crack near her seat.

    What a rush. “I found it!”

    With great astonishment and gratitude, the old lady responded, “I haven't the words to express my thanks!”

    As a young boy, I sometimes traveled the country roads with my dad. He was a rural mill carrier, and on Saturdays he would ask me to go with him. Driving through the countryside was always an adventure: There were animals to see, people to visit, and chocolate cookies if you knew where to stop, and Dad did.

    In the spring, Dad delivered boxes full of baby chickens, and when 1 was a boy it was such a fun to stick your finger 'through one of the holes of the boxes and let the baby birds peck on your fingers.

    On Dad' s final day of work, it took him well into the evening to complete his rounds because at least one member from each family was waiting at their mailbox to thank him for his friendship and his years of service. "Two hundred and nineteen mailboxes on my route." he used to say, "and a story at every one. " One lady had no mailbox, so Dad took the mail in to her every day because she was nearly blind. Once inside, he read her mail and helped her pay her bills.

Mailboxes were sometimes used for things other than mail. One note left in a mailbox read. "Nat, take these eggs to Marian; she's baking a cake and doesn't have any eggs. " Mailboxes might be buried in the snow, or broken, or lying on the groom:. bat the mail was always delivered On cold days Dad might find one of his customers waiting for him with a cup of hot chocolate. A young wrote letters but had no stamps, so she left a few button on the envelope in the mailbox; Dad paid for the stamps. One businessman used to leave large amounts of cash in his mailbox for Dad to take to the bank. Once, the amount came to 8 32,000.

    A dozen years ago, when I traveled back to my hometown on the sad occasion of Dad's death,  the mailboxes along the way reminded me of some of his stories. I thought I knew them all, but that wasn't the case.

    As I drove home, I noticed two lamp poles, one on each side of the street. When my dad was around, those poles supported wooden boxes about four feet off the ground. One box was painted green and the other was red, and each had a long narrow hole at the top with white lettering: SANTA CLAUS, NORTH POLE. For years children had dropped letters to Santa through those holes.

    I made a turn at the comer and drove past the post office and across the railroad tracks to our house. Mom and I were sitting at the kitchen table when I heard footsteps. There, at the door, stood Frank Townsend, Dad's postmaster and great friend for many years. So we all sat down at the table and began to tell stories.

    At one point Frank looked at me with tears in his eyes. " What are we going to do about the letters this Christmas?" he asked.

    "The letters?"

    'I guess you never knew. "

    "Knew what?"

    " Remember, when you were a kid and you used to put your letters to Santa in those green and red boxes on Main Street? It was your dad who answered all those letters every year. "

    I just sat there with tears in my eyes. It wasn't hard for me to imagine Dad sitting at the old table in our basement reading those letters and answering each one. I have since spoken with several of the people who received Christmas letters during their childhood, and they told me how amazed they were that Santa had known so much about their homes and families.

For me, just knowing that story about my father was the gift of a lifetime.

    For those concerned about wrinkly old skin, It might be a creative solution: an elastic(有弹性的) “second skin” that can be smoothed on to make aged tissue look more youthful.

    The wearable film, developed at the Massachusetts Institute of Technology (MIT), has shown promise in a series of small experiments where it was applied to wrinkles, under-eye bags and areas of dry skin. When applied to the face or body, the thin, transparent layer sticks to the skin and supports the tissue, making it look and behave like younger skin, its producers claim.

    “What we've been able to do is create a cream that you can put on the skin, and then when it's on the skin it can actually form, essentially, an elastic second skin,” said Bob Langer, who led the research. Tests in the lab found that the polymer film (高分子膜), which is only 70 thousandths of a millimetre thick, reduced the appearance of wrinkles and under-eye bags, and helped keep moisture in areas of dry skin.

    The layer is designed to be applied in the morning, then peeled off at night. In previous studies, the second skin withstood normal daily wear, and the stresses and strains of exercise and swimming, without falling off or causing irritation. It also survived exposure to rain.

    “It's something you can wear for a whole day or longer, depending on the physical forces thatget applied to the area where it is worn, "said Daniel Anderson, who helped develop the product at MIT. “You can't tell you're wearing it.”

    While normal cosmetics can mask imperfections on the skin, the new coating changes the way skin behaves by giving it the elasticity of young skin. It was developed with help from two companies.

    Natural selection is the process by which one type of animal within a species thrives because of certain characteristics that make it more likely to live than others in its group. The history of the peppered moth（灰蛾）is an example of the natural selection process.

    In 19th century England, certain types of peppered moths were able to better blend（融合）into their surroundings. During that time period, great changes were happening in Great Britain. The Industrial Revolution was part of this change, and with it came air pollution. Natural selection often takes hundred or even thousands of years to occur. For the peppered moth, this process occurred comparatively quickly.

    At the beginning of the Industrial Age, most peppered moths in England were light-colored and covered with black markings, although a few moths had dark-colored wings. Because the light-colored moths blended into the light-colored bark on the trees, they could not be easily seen by birds that would eat them. As the air grew more polluted, however, tree trunks became covered with soot（烟煤）and became darker. The light-colored moths became easy for birds to see against the dark tree trunks. Since the dark-colored moths now had the advantage, their numbers grew. Within 50 years, the peppered moth went from being mostly light-colored to being mostly dark-colored.

    In the 20th century, the air cleared up, and the peppered moth population changed again. As tree trunks lighted due to less soot in the air, light-colored moths once again had an advantage. Their numbers increased as soot levels declined. Depending on their environment, the coloration of the moths helped them to be “naturally selected” to survive.

    By now, you've probably been warned that a robot is coming for your job. But rather than repeat the warning, I've decided to throw down a challenge: man against machine.

    Start with the task we're doing right now: communicating in fluent human. We're sharing abstract ideas through words that we choose with an understanding of their slight difference and impact. We don't just speak in human; we speak as humans. A robot who says that science is fun is delivering a line (念一句话). A human who says that science is fun is telling you something important about being alive.

    Here's another inbuilt advantage we take for granted: as humans we are limited by design. We are bound in time: we die. We are bound in space: we can't be in more than one place at a time. That means when I speak to an audience, I am giving them something special. It's a custom-made, one-off, 100% robot-free delivery, from today's one-and-only Australian Chief Scientist.

    True, I now come in digital versions, through Twitter and Facebook and other platforms, but the availability of those tools hasn't stopped people from inviting me to speak in person. Digital Alan seems to increase the appetite for human Alan, just as Spotify (a digital music service) can increase the demand for a musician's live performances.

    Thanks to technology, many goods and services are cheaper, better and more accessible than ever before. We like our mass-produced bread, and our on-tap lectures and our automated FitBit advice. But automation hasn't killed the artisan bakery (面包店). Online courses haven't killed the booming, alongside their machine equivalents.

    Here's a third argument for the win. We humans have learned the habit of civilization. Let me explain this point by a story. A few years go, some researchers set out to study the way the people interact with robots. They sent out a small robot to patrol (巡逻) the local mall. That robot had a terrible time, and the villains of the story were children. They kicked him, bullied him, and smacked (掌击) him in the head.

    The point is not that the children were violent. The point is that the adults were not. They restrained whatever primitive impulse (冲动) they might have felt in childhood to smack something smaller and weaker in the head, because they had absorbed the habit of living together. We call it civilization. If we want artificial intelligence for the people, we'll need every bit of that civilizing instinct.

    Together, these points suggest to me that humanity has a powerful competitive edge. We can coexist with our increasingly capable machines and we can make space for the full breadth of human talents to flourish.

    Since the first Earth Day in 1970, Americans have gotten a lot “greener” toward the environment. “We didn't know at that time there even was an environment, let alone that there was a problem with it,” says Bruce Anderson, president of Earth Day USA.

    But what began as nothing important in public affairs has grown into a social movement .Business people, political leaders, university professors, and especially millions of grass-roots Americans are taking part in the movement. “The understanding has increased many, many times,” says Gaylord Nelson, the former governor from Wisconsin, who thought up the first. According to US government reports, emissions (排放)from cars and trucks have dropped from 10.3 million tons a year to 5.5 tons .The number of cities producing CO beyond the standard has been reduced from 40 to 9. Although serious problems still remain and need to be dealt with, the world is a safer and healthier place. A kind of “Green thinking” has become part of practices.

    Great improvement has been achieved. In 1988 there were only 600 recycling programs; today in 1995 there are about 6,600. Advanced lights, motors, and building designs have helped save a lot of energy and therefore prevented pollution.

    Twenty –five years ago, there were hardly any education programs for environment. Today, it's hard to find a public school, university, or law school that does not have such a kind of program. “Until we do that, nothing else will change!” say Bruce Anderson.