The oddness of life in space never quite goes away. Here are some examples.

    First consider something as simple as sleep. Its position presents its own challenges. The main question is whether you want your arms inside or outside the sleeping bag. If you leave your arms out, they float free in zero gravity, often giving a sleeping astronaut the look of a funny balled （芭蕾）dancer. “I'm an inside guy,” Mike Hopkins says, who returned from a six-month tour on the International Space Station. “I like to be wrapped up.”

    On the station, the ordinary becomes strange. The exercise bike for the American astronauts has no handlebars. It also has no seat. With no gravity, it's just as easy to pedal violently. You can watch a movie while you pedal by floating a microcomputer anywhere you want. But station residents have to be careful about staying in one place too long. Without gravity to help circulate air, the carbon dioxide you exhale (呼气) has a tendency to form an invisible （隐形的）cloud around you head. You can end up with what astronauts call a carbon-dioxide headache.

    Leroy Chiao, 54, an American retired astronaut after four flights, describes what happens even before you float out of your seat,”Your inner ear thinks your're falling . Meanwhile your eyes are telling you you're standing straight. That can be annoying—that's why some people feel sick.” Within a couple days —truly terrible days for some —astronauts' brains learn to ignore the panicky signals from the inner ear, and space sickness disappears.

    Space travel can be so delightful but at the same time invisibly dangerous. For instance, astronauts lose bone mass. That's why exercise is considered so vital that National Aeronautics and Space Administration (NASA) puts it right on the workday schedule. The focus on fitness is as much about science and the future as it is about keeping any individual astronauts return home, and, more importantly, how to maintain strength and fitness for the two and a half years or more that it would take to make a round-trip to Mars.

    Your house may have an effect on your figure. Experts say the way you design your home could play a role in whether you pack on the pounds or keep them off. You can make your environment work for you instead of against you. Here are some ways to turn your home into part of your diet plan.

    Open the curtains and turn up the lights. Dark environments are more likely to encourage overeating, for people are often less self-conscious(难为情) when they're in poorly lit places — and so more likely to eat lots of food. If your home doesn't have enough window light, get more lamps and flood the place with brightness.

    Mind the colors. Research suggests warm colors fuel our appetites. In one study, people who ate meals in a blue room consumed 33 percent less than those in a yellow or red room. Warm colors like yellow make food appear more appetizing, while cold colors make us less hungry. So when it's time to repaint, go blue.

    Don't forget the clock — or the radio. People who eat slowly tend to consume about 70 fewer calories(卡路里) per meal than those who rush through their meals. Begin keeping track of the time, and try to make dinner last at 30 minutes. And while you're at it, actually sit down to eat. If you need some help slowing down, turning on relaxing music. It makes you less likely to rush through a meal.

    Downsize the dishes. Big serving bowls and plants can easily makes us fat. We eat about 22 percent more when using a 12-inch plate instead of a 10-inch plate. When we choose a large spoon over a smaller one, total intake(摄入) jumps by 14 percent. And we'll pour about 30 percent more liquid into a short, wide glass than a tall, skinny glass.

    For twenty years, I saved all my college course notes and textbooks: that's a lot of paper.  Worse, it wasn't easy to carry them around—and trust me, they weren't light — on at least seven moves. Yet I never once looked at them. They sat in our basement, covered in a thick layer of dust. If books and papers could wonder, they'd wonder why they were still under our stairs after all those years. What were my plans for them? When would the Big Day come?

    Well, the Big Day eventually did arrive; only it was different than expected. My wife, always more accepting changes than I am, finally convinced me to clear out the entire mess.

    The pain I experienced was also unexpected. I didn't feel nostalgia(怀旧的), or suffer pains for long-lost magical moments of my education. No, what hurt me was to come across those terrible papers I'd written, reminders of poor study habits, immaturity(不成熟), and an embarrassing lack of comprehension. It was great to get rid of them. I won't have to carry those dusty, filthy(脏兮兮的) things on our next move. But it was also a clearing of personal history. Initially, I struggled with this. My books, my notes, and my papers were primary source materials, documenting an important time in my life. To clear them out was to clear out the truth. What I've learned since taking this leap is that the lesson is more important than the truth. I feel as if much of my real education during my college years isn't in the documents but now in me. So I am glad to free myself of this physical burden of carrying them around. And what's better is that I don't need to look back on those painful moments. They belong to the past.

    You might want to consider doing something similar, either under the stairs of your basement or in your mind. Not so long ago, a very smart person created a new holiday—Discardia!—to be celebrated four times a year. It's a great idea, and every time I clear things out, I feel better physically and psychologically. Discardia's slogan is “Let go of everything that doesn't make your life awesome!” What is the personal rubbish piling in your life? Clear it out and make your life awesome.

    Some young Cambodians are learning a new sport — skateboarding. The country's first skateboard park is located on the grounds of a local charity group at the edge of Phnom Penh, the capital.

    Sports like Khmer boxing and soccer are wildly popular in Cambodia. But Chea, who has been skating for 6 months, says skating has already become his favorite sport.

    The skaters are learning tricks like launching off a jump or half-pipe and flying through the air on their narrow wooden boards.

    A non-governmental organization called Skateistan Cambodia organizes weekly programs at the park. Skateistan started its work in Afghanistan years ago. Rory Burke is working with the group which expanded to Cambodia last year.

    Rory Burke points out, "Yeah, it's definitely not a typical Cambodian pastime (消遣). And I think the idea of 'why skateboarding is that it's not been done before here. We want to use skateboarding as something saying, 'Hey, this is new, this is something different. And that kind of itself becomes a little bit of hook. People see it and they think and they say, "Wow, 'what is that?', and they want to get involved. "

    Skateistan partners with local groups that work with young people. The park is on the grounds of the group known as PSE, where children attend school and learn a trade. There are almost one hundred twenty participants. They all come from troubled lives.

    Seventeen-year-old Sang Rotha is a student at PSE. "Sometimes I don't do well on subjects like math," he says, "I feel bad when I find it hard to keep up with my lessons. So that is why I skateboard—to improve my bad feelings. "

    He says he began skateboarding more than a year ago. Before he started training, it seemed very easy. But it was very difficult to learn tricks, and he got hurt a lot from falling off.

    Rory Burke says learning to deal with the difficulties is part of the lesson for these young skateboarders.

    The Notre Dame fire has been put out, but its spire and a large portion of its wooden roof have been damaged. The terrible destruction causes a sudden sharp pain to people around the world. On Chinese social media network Wechat a common comment on the disaster is: "What a pity that we cannot see the damaged parts of the wonder anymore."

    But the good news is that there is at least one way of seeing them, namely via a video game called Assassin's Creed: Unity. In this game, the player can travel to one city after another and enter the buildings exactly like what they are in reality, and see Notre Dame as it was before the fire. Further, with virtual reality technology, which is already quite mature, one can even look around the undamaged Notre Dame as if it is still there. Maybe digital technology could help to better protect architectural cultural heritage.

    The idea of digitizing ancient buildings, making digital models of them so their data can be saved, dates back to the 1990s and the necessary technology has continued to advance since then. By scanning the ancient buildings with lasers, building 3D models with multiple images, as well as measuring everything precisely, engineers can make a copy as accurate as the real one.

    As computers and smartphones are hugely popular, the digital replica（复制品）has great use value  First, it allows tourists to feel the cultural relics without touching them, which helps protect them. The virtual tour of Dunhuang Grottoes in Gansu Province is a good example of this as tourists can view the paintings without standing near them. Furthermore, it can make the digitized cultural relics more famous by spreading awareness about them via the Internet. In 2000, a virtual tour of the Great Wall became very popular at the Hannover World Expo, which increased the number of foreign tourists visiting the site in the following years. Above all, it preserves all the information of the cultural relics. Even if the original ones are damaged one day, people can still know what they were like and can build a replica if desired.

    Of course, however precise a model is, it is not the original. Time is the biggest threat to a country's architectural heritage, which will always become ruins with the passing of time. Maybe we will have better technologies in the future, but the digital technology offers a practical way to preserve architectural cultural heritage at the moment.

A teenager needs to have a sense of independence in their life to feel secure(安全的). To some teenagers independence means a lot to them, and I think that some parents don't allow their teenagers enough independence.

Independence has something to do with freedom. Some kids are not allowed to go anywhere alone, and the only thing their schedule includes is going to school, coming home, going to sleep, and repeating the process the next day. Parents tend to be afraid that their kids can get hunt if they go outside into the world. But if parents control their kids too much, they may never learn to live on their own. The best way for a teenager to learn lesson is through experience. I think it is beneficial for teenagers to have freedom.

Teenagers' lack of freedom can also stop them from having good friendship at school. Some might say this is a good thing, because it helps them focus more on their school work. I argue that this can only discourage them not to do their school work. Some parents do not allow their children to be around their friends outside the school, thinking that this will get them into trouble. But I don't think so. Instead, isn't this a good reason for parents to get their children a cellphone? Cellphones allow teenagers to stay in touch with their parents, and communicate with friends.

Privacy is another issue between parents and their teenagers.Teenagers tend to enjoy relaxation by themselves in their own room. This also gives them a sense of independence. It often annoys teenagers when their parents enter their room when they are not home. I know that my mom always goes in my room when I'm not home, and this has brought me to the point where I have asked many times to get a lock on my door.