Nuclear power's danger to health, safety, and even life itself can be summed up in one word: radiation.

    Nuclear radiation has a certain mystery about it, partly because it cannot be detected by human senses. It can't be seen or heard, or touched or tasted, even though it may be all around us. There are other things like that. For example, radio waves are all around us but we can't detect them, sense them, without a radio receiver. Similarly, we can't sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.

    At very high levels, radiation can kill an animal or human being immediately by killing masses of cells in vital organs. But even the lowest levels can do serious damage. There is no levels of radiation that is completely safe. If the radiation does not hit anything important, the damage may not be serious. This is the case when only a few cells are hit, and if they are killed immediately. Your body will replace the dead cells with healthy ones. But if the few cells are only damaged, and if they reproduce themselves, you may be in trouble. They can grow into cancer. Sometimes this does not show up for many years.

    This is another reason for some of the mystery about nuclear radiation. Serious damage can be done without the victim being aware at the time that damage has occurred. A person can be irradiated(辐射)and feel fine, then die for cancer five, ten, or twenty years later as a result. Or a child can be born weak as a result of radiation absorbed by its grandparents.

    Radiation can hurt us. We must know the truth.

    Since 2013,Torobo, a robotic are designed to test the limits of artificial intelligence, has had one ambition—to be admitted to the University of Tokyo, one of Asia's top-ranked educational institutions. Although equipped with an extensive database of textbooks and other teaching materials, Torobo has repeatedly failed to obtain the university's required minimum 80% score in the National Center Test, a yearly standardized entrance examination adopted by Japanese universities. This year was no exception.

    In early November, Torobo, along with millions of Japanese high school students, took a mock(模拟的)exam to prepare for the all-important standardized test.

    Torobo's total score of 525 out of 950, which was higher than the national average, was enough for it to get admitted to many other influential Japanese universities.

    However, its standard score of 57.1%, though 14 points higher than in 2015, still fell short of the minimum required for the University of Tokyo.

    A closer analysis of the results showed that Torobo was able to draw from its database to solve knowledge-based questions and ones involving complex mathematical calculations, but it had a hard time thinking independently, failing to comprehend multiple sentences and phrases to arrive at the logical conclusions. This weakness was reflected in its shabby English scores.

    Fortunately, the robot's creators have decided to free Torobo from its four-year sufferings. Noriko Arai, professor of the University of Tokyo who heads the team, says, “From the present results, we are able to evaluate the possibilities and limits of artificial intelligence. From now on, we will grow its abilities in the fields where it is doing well and aim to improve them to levels that can be applied in industry.” So while Torobo will never graduate from the University of Tokyo, it can still look forward to a bright future!

    Fourth-grade teacher Tori Nelson allowed one of her students to shave her head in the schoolyard, after bullies（仗势欺人者） teased him about his own buzz cut. Ms. Nelson got the idea after noticing that Matthew Finney, a shy boy from her homeroom at Winlock Miller Elementary School in Washington State, was standing outside his classroom crying and wearing a winter hat.

    Ms. Nelson could see the back of his neck had been shaved, and since Matthew usually had very thick curly brown hair, she realized that he'd had a haircut over the weekend. She asked him what was wrong， and he said he'd gotten a buzz cut for the summer. But this morning, a fifth grader on the bus made fun of him, and he didn't want to come to class and get laughed at by other kids. Ms. Nelson tried to convince Matthew to come inside, but since school rules banned kids from wearing hats indoors he refused—explaining that he was afraid of showing his haircut to the other children in case they also made fun of him.

    "Finally I said, 'If you take your hat off and come to class, I'll let you give me a buzz cut too,' Ms. Nelson told Yahoo Parenting." I figured it's just hair, and mine is already short anyway. I might as well get it shorter in time for the warm weather.

    Matthew excitedly took her up on the offer, and Ms Nelson and another teacher gathered all the fourth graders together during break time. A school employee brought in scissors, which Matthew used to the cheers of his classmates, excitedly watching as their teacher's hair fell away onto the ground in the schoolyard.

    "It was a lot of fun for the kids, and it helped Matthew feel better about himself." said Ms Nelson." You have to do what it takes to reach children. Teaching isn't just about reading and writing: it's about self-worth and accepting differences.

    Hobbies in general are becoming something of the past. Our lives are already filled with classes, homework, working, relationships and sleeping. When we do have a spare moment, it is all too easy to spend it on the endless entertainment and media that are right at our fingertips.

    I do not doubt that there are some people who could become a great writer or musician. I only fear that so many people are busy pursuing their education and their careers, but they never even see the potential (潜能) they have. The next great photographer or singer could be going to college right now. But they might not even know they have a gift for photographing or singing if they've never picked up a camera or a guitar.

    Of course, the final goal of pursuing a new hobby shouldn't be to become rich and famous. For most people, a hobby is just something they enjoy doing for the purpose of the thing itself. Such hobbies are still very useful. Studies have shown that people who have a hobby are less likely to have stress and more likely to have more meaningful lives.

    Most importantly, a hobby is just something you do to make you happy. I hate to break it to you, but we all have a long lifetime of work and stress ahead of us. It will make things much easier if we can practice the piano or make some collections after work.

    Sure, it's not easy to start a new hobby while going to school, but it will likely never get easier than it is right now. So think about the thing that you have always wanted to try but were too embarrassed or busy or whatever. You never know, you might become the world's next great people. If not, you'll at least be a little more well-rounded, more interesting and less stressed.

    The Largest World Fairs of All Time

    New York World Fair — New York, 1939

    The 1939 New York World Fair was the largest exposition (博览会) in US history with visitors over 14 million. The Fair was planned during the Great Depression and was aimed at relieving the city from economic depression by attracting foreign investment. Major inventions to emerge (出现) at the New York World Fair included nylon fabric, a streamlined pencil sharpener, and a futuristic car city imagined by General Moiors.

    Exposition liniverselle — Paris, 1900

    The Exposition Universelle was one of the earliest expositions to feature multiple countries with France inviting various countries to display their technological advancements and cultural heritage. Exposition Universelle was the birthplace of many inventions that we enjoy today including escalators (自动扶梯) and talking films.

    Expo' 70 — Osaka, Japan

    Expo' 70 was the biggest exposition of the 20th century and the second largest in history. Expo 70 had a record attendance of over 64 million visitors, a 40-year record that would not be broken until Expo 2010 in Shanghai. Notable exhibitions included a large piece of moon rock that was brought back from the Apollo 12 mission.

    Expo 2010 — Shanghai. China

    Expo 2010 goes down as the largest fair in history, having attracted 73 million people. It also had the highest international participation of any exposition in the world with 246 countries participating. The opening ceremony featured the biggest LED screen in the world as well as one of the biggest fireworks displays in history.