We once had a poster competition in our fifth grade art class.

    “You could win prizes,'' our teacher told us as she wrote the poster information on the blackboard. She passed out sheets of construction paper while continuing, “The first prize is ten dollars. You just have to make sure that the words on the blackboard appear somewhere on your poster.”

    We studied the board critically. Some of us looked with one eye and held up certain colors against the blackboard, rocking the sheets to the right or left while we conjured up our designs. Others twisted their hair around their fingers or chewed their erasers while deep in thought. We had plans for that ten-dollar grand prize, each and every one of us. I'm going to spend mine on candies, one hopeful would announce, while another practiced looking serious, wise and rich.

    Everyone in the class made a poster. Some of us used parts of those fancy paper napkins, while others used nothing but colored construction paper. Some of us used big designs, and some of us preferred to gather our art tidily down in one corner of our poster and let the space draw the viewer's attention to it. Some of us would wander past the good students' desks and then return to our own projects with a growing sense of hopelessness. It was yet another grown-up trick of the sort they seemed especially fond of, making all of us believe we had a fair chance, and then always — always — rewarding the same old winners.

    I believe I drew a sailboat, but I can't say that with any certainty. I made it. I admired it. I determined it to be the very best of all of the posters I had seen, and then I turned it in.

    Minutes passed.

    No one came along to give me the grand prize, and then someone distracted me, and I probably never would have thought about that poster again.

    I was still sitting at my desk, thinking, What poster? when the teacher gave me an envelope with a ten-dollar bill in it and everyone in the class applauded for me.

    Teenagers who spend hours in front the television may have a poorer diet as young adults.

    A study, which included nearly 1,400 high school students, found those who watched TV for five hours or more per day had less healthy diets than peers(同龄人) five years later. Why does this happen? Should the parents take any measures?

    On the one hand, people who spend a lot of time in front of the TV, especially teenagers, may snack more, and that may affect their long-term diet quality.

    On the other hand, TV ads for fast food, sweets and snacks tempt teenagers to eat more of those foods. And TV time might also replace exercise time for some kids.

    Lead researcher Dr. Daheia J. Barr-Anderson, of the University of Minnesota in Minneapolis, told Reuters Health a clear correlation between TV time during high school and diet quality in young adulthood. While the heaviest TV viewers were eating the most junk food, those who'd watched less than two hours per day had the highest intake(吸收) of fruits, vegetables, whole grains and high-calcium food. In her opinion, parents should limit and monitor TV viewing.

      As far as I am concerned, children should watch no more than two hours of television per day. And parents should set a good example by eating right, being physically active and curbing their own TV time.

    Chinese writers seldom win a big prize in the world. One of those prizes is the Hans Christian Andersen Prize, the highest honor in the world that can be given to an author and an illustrator of children's books. No Chinese writer had ever won it, until April 4, 2016, when 62-year-old Cao Wenxuan received the prize. Cao received the honor at the Bologna Children's Book Fair in Italy.

    Patricia Aldana praised Cao's “deeply humanistic” books. These novels admit that life can be sad for children.

    Instilling children with good virtues for the sake of humankind is something that Cao stresses. He said, “It's time for us to alter our understanding of reading. Books should bring not only joy to young readers, but also have their ideas about life.”

    That feature of his works has touched many adults too. “The common choice of the judges, Cao writes beautifully about the lives of children facing great challenges,” said Aldana.

    After his success, Cao praised good translation for bringing attention to his work. Chinese children's literature could get high honor in the world if it were correctly translated in a style that could be easily understood, he said.

    Other writers, including Jin Bo, have also blamed poor translation as the reason why Chinese literature fails to get honor in the world. Jin was named for the Hans Christian Andersen Prize in 1992, but at that time, he had to translate, in a hurry, several paragraphs from his book to give to the judges. "On one hand, the jury has little knowledge of Chinese authors. On the other hand, it is we ourselves who didn't introduce our work and promote (促进) ourselves enough," he said in a class in 2013.

    Whenever we see a button, we are eager to press it because we know something will happen. This is true in most cases, for example on a doorbell and on the "on/off" button on the TV. But some buttons are actually fake, like the "close" button on a lift.

    Many people are in the habit of pressing the "close" button because they don't have the patience to wait for the lift doors to shut. But lifts "close" buttons are a complete scam, at least in the US-the doors will not close any faster no matter how hard you press.

    It started in the 199os when the Americans with Disabilities Act was passed in the US, making sure that all lifts stayed open long enough so that people with disabilities could enter. Only US firefighters and repairmen can use the buttons to speed up the door-closing process if they have a code or special keys.

    But to normal lift riders, the buttons aren't completely useless. According to psychologists, fake buttons can actually make you feel better by offering you a sense of control." Perceived（能够感知的）control is very important. It reduces stress and increases well-being," Ellen J. Langer, a psychology professor, said," Having a lack of control is associated with depression."

    Experts have revealed that a lot of buttons that don't do anything exist in our lives for this same purpose. For example, many offices in the US have fake thermostats（温度调节器）because people tend to feel better when they think they can control the temperature in their workspace.

    But psychologists found it interesting that even when people are aware of these little" white lies", they still continue to push fake buttons because as long as the doors eventually close, it is considered to be worth the effort.

   "That habit is here to stay," John Kounios, a psychology professor, said," Even though I have real doubts about the traffic light buttons, I always press them. After all, I've got nothing else to do while waiting.  So why not press the button in the hope that this one will work?"

On paper, hydrogen (H2) looks like a dream fuel. Coal, oil, and natural gas produce carbon dioxide, which warms the earth when burned, Hydrogen produces pure water. Hydrogen packs more energy into less space than a battery (but certainly less than petrol) . Also, empty tanks (燃料箱) can be refilled with hydrogen much faster than refilling empty batteries with electricity.

While in practice, things are trickier. Storing a meaningful amount of hydrogen gas requires pressing it several hundred-fold. Changing it into the liquid form is another option, but it should be cooled to-253C. Both processes require a heavy and strong tank. While a 700 bar tank is acceptable for a city bus or a truck, adapting it for use in small vehicles is very difficult because the pressure during refilling would be too great.

The solution? Powerpaste.

A German team of researchers, led by Marcus Vogt, have come up with an interesting "powerpaste", which can store hydrogen energy at atmospheric pressure, ready for release when needed. It is so named because it comes in tubes and looks like toothpaste (牙膏) , not in its traditional form of gas.

The main ingredient (原料) of the paste is magnesium hydride, a substance that reacts with water to form hydrogen. The escaped hydrogen can then be directed into a fuel cell, where it reacts with oxygen from the air to produce electric power.

Refueling is very simple, as instead of going to a filling station, drivers and riders can simply replace an empty tube with a new one and refill the water tank.

Given that powerpaste only begins to break down at temperatures of around 250℃ it remains safe even when a vehicle stands in the baking sun for hours.

However, we will have to be patient. Just because researchers have succeeded in developing a new fueling way does not mean that we can expect to see such vehicles on the road anytime soon. It will indeed be several years before this concept is turned into reality.