The Leaning Tower of Pisa was straight like a pole when the construction began in 1173. It started to shift direction soon after construction because of poor foundation in addition to the loose layer of subsoil(底土). At the beginning, it leaned to the southeast before the shaky foundation started to shift leaning towards the southwest. After the period of structural strengthening at the beginning of the 21^st century, now the Leaning Tower of Pisa leans at an angle of 3.97 degrees.

    In 1178, the shift in direction was observed for the first time when the construction had progressed further to the third floor. The tower was heavy for the three-meter foundation that was built on a weak area of land.

    For compensating(补偿) the leaning position, the builders started to construct the upper floors with one side higher than the other one. This caused the tower to lean in the other direction. This unusual structure led to the tower being actually curved. In spite of these efforts, the tower kept on leaning.

    The government of Italy started to plan prevention of the complete collapse of the tower in 1964. However, a request was put forward by the authorities to keep the leaning position because of the tourism industry of the region.

    After nearly two decades of careful planning by engineers, historians and mathematicians, the stabilization efforts for the Leaning Tower of Pisa started in 1990. The tower was closed for the general public and the people living nearby moved away. For reducing the total weight of the tower, its seven bells which represented the seven musical notes were removed. The tower was reopened for the general public on December 15, 2001.

    In May 2008, after removing another 70 metric tons of earth, the engineers announced that the tower had been finally stabilized and it would remain stable for at least 200 years.

    Experts generally consider BMI for kids to be a good measure of body fat, at least among heavier children. But in some cases it might be misleading. Athletic kids, in particular, may fall into the overweight category when they are actually muscular.

    Your child's BMI is important, but it is only a piece of the picture. If a BMI percentile (体重指数) indicates that your child is not within the healthy range, she needs a complete weight and lifestyle evaluation with a doctor.

    Experts recommend that kids of all ages and all weight categories follow these healthy guidelines to keep weight in control. It's easy to remember them as “5 — 2 — 1 — 0” every day.

    5 > Everyone in your family needs five servings of vegetables and fruit. Keep serving them even if kids don't eat them. If they see a food over and over, they're more likely to try it in the end.

    2 > Limit TV-watching to no more than 2 hours a day. Family members who use other “screens”—video games or computers, for instance, get less TV time. And kick the TV out of all bedrooms.

    1 > Get 1 hour of physical activity. Add up the minutes each family member is moving —it should be 60 minutes or more for each person. Start small and keep adding if necessary.

    0 > That's how many sugar-sweetened beverages you should have a day. Juice drinks such as lemonade and fruit punch, sodas, tea, and coffee can all have added sugar. Stick to water and reduced-fat milk instead.

    Skateboarding is an action sport which includes riding and performing tricks using a skateboard, as well as an activity for fun, an art form, an entertainment industry job, and a method of transportation. In 2016, it was announced that skateboarding will be represented at the 2020 Summer Olympics in Tokyo, Japan.

    There are various theories about the origins of Skateboarding, but it is generally held that the sport began in the 1940s on the west coast of the USA when metal wheels were attached to a narrow wooden board. In the 1950s, plastic replaced metal as the material of choice for the wheels, and the first "Roller Surfboard" become commercially available, which in turn developed into the skateboard that we know today. The sport was a big hit with the younger generation and grew in global popularity in the 1980s and 1990s. Since the late 1990s, skateboarding has become an important part of street culture.

    However, skateboarding has raised heated discussions in areas where the activity, although legal (合法的), has damaged stone works, steps, benches, and parks. Certain cities oppose the building of skate parks in their neighborhoods, for fear of increased crime (犯罪) and drugs in the area. The disagreement between the old image of skateboarding and a newer one is quite obvious: magazines such as Thrasher describe skateboarding as dirty, and still firmly tied to punk (朋克), while other publications, Transworld Skateboarding as an example, paint a more different and controlled picture of skateboarding. As more professional skaters use hip hop, or hard rock music in their videos, many urban youths, hip-hop fans and hard rock fans are also drawn to skateboarding, weakening the sport's punk image. Besides, group spirit influences the members of this community. In presentations of skateboarding, the evidence of crime is absent, and no attempt is made to tie extreme sports to any kind of illegal activity.

    The good news is that efforts have been made to improve recognition of the cultural heritage as well as positive effects of skateboarding in cities. By raising £790,000, the Long Live Southbank initiative managed to stop the destruction of a forty years old spot in London due to urban planning, a rescuing operation whose effect extends beyond skateboarding. The presence of skateboarders on this public space keeps the area under nearly constant watch and drives homeless people away, increasing the feeling of safety in the area. The activity attracts artists such as photographers and film makers, as well as a significant number of tourists, which in turn drives economic activity in the neighborhood.

    When we do the same movements with our bodies over and over again, we overuse some muscles. And that overuse can lead to strain(紧张)and injury. Sometimes those problems can come from doing sports. But exercise experts say they are now seeing another cause for muscle problems: hand-held technology devices(设备).

    Staring down at your phone or tablet for long periods of time puts great tension on your neck and spine(脊椎). Many people who use tech devices also bend their shoulders forward. Experts say this posture(姿势)puts strain on the entire upper body. Muscle strain linked to hand-held technology has become such a common condition that it now has a name: tech neck.

    Kimberly Fielding, an exercise teacher in New York City, explains that constantly looking down at our devices creates an unnatural bend in our spine. This can cause nerve pain and other problems. “A lot of the curves of the neck can change, so instead of the neck spine going inward, the curve can be a little bit different and it causes nerve pain and disc herniation(椎间盘突出)and different muscle tension headaches — different things that really can reduce quality of life.”

    Fielding created a class to directly solve the problem of tech neck. The class uses different exercises to release tension in the upper body and strengthen back and neck muscles. Fielding says these exercises may feel uncomfortable in the beginning because the neck muscles may have become weak.

    However, you don't need to take a class like Fielding's. You can take simple steps to improve tech neck. For a quick fix, hold your phone at eye level. At the same time, take breaks from using your technology by standing up and stretching your legs often. Also, give your eyes a break by closing them throughout the day.

    My challenge for you is this: to read a book for 15minutes every single day for a month.

    Let me explain a bit, by telling you where the challenge came from. I have many things in common with my dad, like music taste and sense of humor, but sadly reading isn't one of them. I can happily spend a whole day with a book, but my dad can't read a book for longer than about 5 minute. He reads emails, websites and papers for work, but not book. He's busy, so I think sitting down to read for just 15minutes a day is a good way to relax and to introduce him to reading.

    My dad is not the only person who avoids book. I know lots of people would rather relax on their computers or in front of the TV. Everyone is different and has their own interests, but I think there are lots of benefits to reading, which screen﹣based activities don't have.

    Firstly, it's better for your eye. Looking at screens can be very stressful for your eye muscles, and clearly you should avoid looking at screens for an hour before bed, to get a good night's sleep.

    One thing I personally love reading, is being transported to another world﹣I often forget the time or things around me! Reading is a great way to switch off before you go to bed, because you think more about the world of the book, rather than the real world, so you can truly relax. I know you can be transported to a different world in a film or a TV show, but I think books do it better.

    I also enjoy hearing what people are doing and finding out what they think. Reading gives me the chance to get to know hundreds of new people! It also teaches you to see things from other people's point of view, and understand other people's decisions or opinion. With a book, you can hear everything a character is thinking or feeling﹣you really can be inside someone else's head!

    So give it a go! Take 15 minutes when you are waking up, going to bed, eating lunch, or having a coffee. If you read a lot, why not try 15 minutes of an English book, or pass the challenge on to someone else？ Good luck, and happy reading!

    Once again DC Comics and Warner Bros. have divided fans and critics over their latest superhero film.

    There had been worrying news about Justice League in the months before its release, with a lot of reshoots of scenes, a new director being brought in to finish the film after original director Zack Snyder's tragic loss of his daughter and, of course, a lot of talk about Ben Affleck's future in the role of Batman.

    Some people are saying that Justice League is another big disappointment, that it could have been incredible and instead fails to really entertain. Others say that Warner Bros. have finally got it right and that the future for the League looks bright.

    My opinion lies somewhere in the middle. The film was by no means a disappointment: it was exciting, funny and a lot of fun to watch. There's something special about watching the heroes from your childhood brought to life on the big screen and maybe that is affecting my opinion.

    However, I will say that a lot of work needs to be done if the producer wants to make a great success. Although the film was good, it was obvious which scenes had been reshot and how the characters had been changed. I also have to mention the several scenes in which the special effects were very badly done; these are the kinds of problems that you don't expect to see in a film with such a big budget.

    Another point to add is that it is good to see the producer making Superman slightly a brighter character and adding some jokes to the plot to keep things fun. But the producer must be careful not to make the mistake that another film producer—here, not mentioning the name—is coming very close to doing: turning all of the films into bright and colorful shows and losing a lot of seriously good stories.

    In the end, Justice League is not a perfect film but it is definitely not a terrible one. A lot of work is still to be done but I hope that DC does not completely lose its darker side.