Many facts suggest that children are overweight (超重的) and the situation is getting worse, according to the doctors. I feel there are a number of reasons for this.

    Some people blame the fact that we are surrounded by shops selling unhealthy, fatty foods, such as fried chicken and ice cream, at low prices. This has turned out a whole generation of grown-ups who seldom cook a meal for themselves. If there were fewer of these restaurants, then probably children would buy less take-away food.

    There is another argument that blames parents for allowing their children to become overweight. I agree with this, because good eating habits begin early in life, long before children start to visit fast food shops. If children are given fried chicken and chocolate rather than healthy food, or are always allowed to choose what they eat, they will go for sweet and salty foods every time, and this will carry on throughout their lives.

    There is a third reason for this situation. Children these days take very little exercise. They do not walk to school. When they get home, they sit in front of the television or their computers and play computer games. Not only is this an unhealthy pastime (消遣), it also gives them time to eat more unhealthy food. What they need is to go outside and play active games or sports.

    The above are the main reasons for this problem, and therefore we have to encourage young people to be more active, as well as steering them away from fast food shops and bad eating habits.

    My elder cousin Ted liked complaining almost about everything. When he faced a problem, he always chose to complain about it instead of finding a way to solve it. That was not right. Ted was healthy and had received a good education. He should and could find a good job and work hard to feed himself, but he just complained all day, drifting from one job to another. One day, I read about a farmer called Chris and told Ted about the farmer.

    Chris works hard, performs many jobs around the farm. But Chris is not exactly like other farmers. What makes him different is that he was born without arms or legs. But this has not stopped him from working hard and getting things done.

    Now, you may ask, is this possible? Like many other amazing people who have no arms or legs, Chris does not focus on what he can't do, but rather on what he can do. And he can do a lot! He drives farm vehicles and looks after crops. Once you see Chris in action, you will think there is nothing he could not do.

    Chris is a great example of a person who is making the most of his gifts. His positive attitude and courage make him a true inspiration.

    After I told Ted about Chris, he became silent. Compared with Chris, Ted was much luckier. Then luckily, I saw Ted's change.

    Do you like complaining? If you do, think about Chris. Such a man chooses to stay positive. Why don't we?

    Adults always think it surprising that they can remember well what they learned as children but have never practiced ever since. A man who has not had a chance to go swimming for years can still swim as well as ever when he gets back in the water. He can get on a bicycle after many years and still ride away. He can play catch and hit a ball as well as his son. A mother who has not thought about the words for years can teach her daughter the poem that begins “Twinkle, twinkle, little star” or remember the story of Cinderella or Goldilocks and the Three Bears.

    One explanation is the law of overlearning, which can be stated as follows: Once we have learned something, additional learning trials (尝试) increase the length of lime we will remember it.

    In childhood we usually continue to practice such skills as swimming, bicycle riding, and playing baseball long after we have learned them. We continue to listen to and remind ourselves of words such as “Twinkle, twinkle, little star'' and childhood tales such as Cinderella and Goldilocks. We not only learn but overlearn.

    The multiplication tables (乘法口诀表) are an exception to the general rule that we forget rather quickly the things that we learn in school, because they are another of the things we overlearn in our childhood.

    The law of overlearning explains why cramming (突击学习) for an examination, is not a satisfactory way to learn a college course, though it may result in a passing grade. By cramming, a student may learn the subject well enough to get by on the examination, but he is likely soon to forget almost everything he learned. A little overlearning, however, is really necessary for one's future development.

    It is 6:00a.m.on the first day of the school year. In Chery brook Technology High School, mathematics teacher Eddie Woo is already at work.

    One of the first things before the first bell rings is to set up his tripod（三脚架）and iPad in the middle of the classroom. “I'm Mr. Woo. I record my lessons. I record all of them. In fact, I'm about to record this one,” he explains to his new maths class.

    He started posting videos online in 2012 for a student who was sick with cancer and missing a lot of school, so he started sharing them across the country and beyond. Wootube now has more than 38,000 subscribes(用户) and has attracted almost 4 million views worldwide.

    Cherybrook Technology High School principal(校长) Gary Johnson said Mr. Woo was helping maths teachers in Australia and making maths popular again. “He has an ability to simplify(简化) maths to a level where kids can really understand it.” Mr. Johnson said.

    12-year-old student Emily Shakespear said Mr. Woo's teaching style made maths easy and interesting. “I don't want to say it, but he sucked me into maths,” she said. Owen Potter, who attends high school in Cobar agreed. “It's difficult to understand how someone in Sydney can influence thousands of people across the whole country,” he said.

    Mr. Woo won the 2017 University of Sydney Young Alumni Award for Outstanding Achievement, and he was one of 12 Australian teachers honored at the Commonwealth Bank Teaching Awards.

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    Fashions have a lot of rules. Most of them, however, are just wrong. But there's one rule that goes beyond tradition and into the field of scientific study of the brain: Black clothes are slimming. It all comes down to how your visual system processes the light. The below holes in each square are the same in size, yet the white hole looks bigger than the black hole.

    In the 1500s, Galileo Galilei noticed that some of the planets looked larger when viewed with the naked eye than they did when viewed through a telescope, making the white light of Venus appear eight to ten times larger than Jupiter in the night sky. He knew something strange must be going on with his vision to cause this illusion, but he wasn't sure what it was. Luckily, scientists never stopped wondering, and in 2014, they figured it out.

    Our visual system operates via two main channels: "on" neurons (神经元) that are sensitive to light things and "off" neurons that are sensitive to dark things. When it came to the dark "off" neurons, the researchers found that they responded predictably to dark shapes on a light background the greater the contrast between the two, the more active these neurons were. But the light on" neurons behaved unpredictably. Even with the same amount of contrast, light objects on a dark background caused a greater response in these neurons.

    This phenomenon makes some sense, evolutionarily speaking. In the dark of night, you'd want to be able to take in every bit of light you can get, so a visual system that enlarges light objects on a dark background could be very useful. However, it's not that hard to see dark objects in the light of day. It has some effects in the colors of your clothes and in the appearance of the planets—the brighter appearance of Venus in the night sky makes it look bigger than the darker Jupiter.