A team of researchers at the University of Illinois at Chicago found that too many kids are eating too much pizza and too many calories are doing harm to children's health.

    "There are a lot of takeaways from the study. But the biggest thing is that parents are serving their kids too much pizza," said Dr. William Dietz, one of the study's authors and the director of the Sumner M. Redstone Global Center for Prevention and Wellness at the Milken Institute of Public Health at the George Washington University.

    The researchers used data from the National Health and Nutrition Examination Survey, which tracked the diets of more than 11,000 children and teenagers. Researchers figured how many children eat pizza in the United States, how often they eat it, and how much they eat when they do.

    Pizza, pretty alarmingly, is the second leading source of calories in the diets of America's children, next only to grain desserts, such as cookies and other sweets. On any given day, roughly 20 percent of all children aged 2 to 11 and adolescents aged 12 to 19 eat pizza. And when they do, they eat a lot of it. When children eat pizza, they eat roughly 400 calories, according to the study. For teenagers, it's upwards of 600 calories.

    All that is pretty problematic, according to Dietz largely because kids don't tend to balance the pizza slices with salads, vegetables and other more nutritional(有营养的) foodstuffs. Days on which children and teenagers eat pizza are not only associated with considerably higher intakes of fat, but also, quite simply, with more food: on average, children consume 84 extra calories on the days they eat pizza, while adolescents consume an extra 230 calories.

    "When you eat extra calories and don't compensate(抵偿) for them at another point of the day or week, it can lead to weight gain and even obesity." Dietz said.

    There is a Silver lining. Pizza consumption is still too high by nutrition standards, but it's lower than it used to be. Consumption(消费) fell by roughly 25 percent between 2007 and 2016, according to the study. Much of that has come at dinner where it's fallen by 40 percent for children and about 33 percent for teenagers. It's unclear whether the decline has been in connection with a growing concern over obesity, especially among the country's youth.

    But the drop in pizza consumption, while significant hasn't been big enough "It's a positive trend," Dietz said. "But we're not quite them yet."

    It's easy to see the appeal of pizza. It's cheap. Parents can buy a lot of pizza for not a lot of money. Besides, they can buy pizza from a chain shop, a mom-and-pop store or a grocery freezer. And it's universally loved. The estimated 3 billion pizza eaten each year in the United States is a proof of the food's unmatched popularity. Given how much the country loves pizza, what's to be done? Dietz suggests pizza with smaller serving sizes and healthier toppings(配料). "We're not suggesting that kids avoid pizza altogether." said Dietz. "But when parents serve it, it's important that they understand it's extremely caloric. They should serve smaller pizza, or at least smaller slices."

    The first organized system for sending messages began in Egypt around 1500 B.C. This system developed because the pharaohs frequently needed to send messages up and down the Nile River in order to keep their empire running smoothly. Later, the Persians developed a more efficient system for sending messages using men and horses. Messages carriers rode along the road system stretching from one end of the Persian Empire to the other. Along these roads, fresh men and horses waited at special stations to take and pass along any messages that needed to be sent. The stations where riders passed messages back and forth were built 23 kilometers apart, so the men and horses were able to travel quickly between them. The Romans later took up his idea and improved it by using a more advanced and extensive road system.

    In China, however, Kublai Khan had built up his own system for delivering messages. This system worked in the same basic way as the Roman system. The difference was that Kublai Khan kept 300,000 horses along the roads of this delivery lines. There were over 10,000 stations where a message would be passed from one rider to another with a fresh horse. In this way, Kublai Khan could receive messages from anywhere in the country in only a few days.

    It was not until the 1500s that a well-organized postal system appeared again in Europe. One family, the von Taxis family, gained the right to deliver mail for the Holy Roman Empire and parts of Spain. This family continued to carry mail, both government and private, throughout Europe for almost 300 years.

    In 1653, a Frenchman, Renouard de Velayer, established a system for delivering post in Paris. Postal charges at that time were paid by the recipient, but de Velayer's system was unique by allowing the sender to pre-pay the charges, in a similar way to the modern stamp. Unfortunately, de Velayer's system came to an end when jealous competitors put live mice in his letter boxes, ruining his business. Eventually, government-controlled postal systems took over from private postal businesses, and by the 1700s government ownership of most postal systems in Europe was an accepted fact of life.

    The thing that all these early systems had in common was that they were quite expensive for public use, and were intended for use by the government and the wealthy. However, in 1840, a British schoolteacher named Roland Hill suggested introducing postage stamps, and a postal rate based on weight. This resulted in lowering postal rates, encouraging more people to use the system to stay in touch with each other, His idea helped the British postal system begin to earn profits as early as 1850. Soon after that many other countries took up Mr. Hill's idea. And letter writing became accessible to anyone who could write. Today, the Roland Hill awards are given each year to "encourage and reward fresh ideas which help promote philately"(stamp collecting).

    I'll never forget the day when Mary came into my office and said, I am too old to learn how to use a computer. I shook my head. Here was a woman who had raised 6 children and who had made great progress in her career telling me that she was too old to learn something new. I told her that I always believed people were never too old to learn.

    Mary followed my advice and did learn how to use the computer. Now, she is retired and leading a very active life volunteering in her community(社区), using her computer skills and helping anyone that needs help.

    When she was in her sixties, one day she called me and said she had played the piano for others all her life, and now she was going to plan to make a CD of her own. My mind flashed back to the day when she told me she was too old to learn. You can imagine my surprise and delight.

    To produce the CD, she had a lot of things to learn. It was not just sitting at the piano and playing. She had to research the songs, learn about copyright(版权), and learn about marketing. It was pretty amazing for someone who once said she was too old to learn. And finally she made it. Now she has her own CD-Mixed Blessings.

    Most of you probably have heard about some people who have gone back to university in their seventies and have also graduated. They are on their way again to charging themselves with a new skill and a new attitude towards life. The point is you are unable to learn anything at any age if you believe you are too old. On the contrary, you can achieve anything at any age if you believe you can.

    As smog forced students to stay home, the online learning industry saw a sharp increase in consumers.

    During the air pollution red alert from Dec. 8 to 10 last winter, the Beijing Commission of Education ordered all kindergartens, primary schools and middle schools to suspend classes (停课). But the commission urged that, "Teachers should guide students to make full use of digital materials and conduct online learning at home".

    According to the China Education and Research Network, the number of new users of 17zuoye. com, an online homework platform, tripled (增至三倍) on Dec. 8 compared to the previous day.

    Online courses companies also adopted special measures to meet students' demand for Internet learning during the red alert period. For example, New Oriental offered free online English classes for three days for school students as well as online question answering services.

    Recent years have seen the popularity of online courses increase sharply in China. Massive Online Open Courses (MOOC), for example, originated in the United States but have become widespread in China since 2013. Some Chinese universities, including Tsinghua University and Peking University, have started their own MOOC platforms. "MOOCs have enlarged the time and space of teaching, fired up learners' interest, helped more people benefit from high quality educational resources and accelerated reform in many aspects of teaching," an official at the Ministry of Education told China Daily.

    Being stuck at home doesn't mean that learning stops. In fact, it's just the opposite. Here are some activities and resources to foster kids' imagination and build their curiosity at home.

    Let's Get Down to the Science

The science lab at school may be closed, but you can still put on goggles and a white lab coat and learn at home. This Test Tube Experiment Kit will make you feel like a genius in no time. Kids will get the chance to learn about basic chemistry, physics, and more by creating pop-resistant bubbles, bouncy balls, and other objects.

    To Infinity (无穷) and Beyond

Earth is a part of the Milky Way galaxy, but did you know there are around 100 million galaxies in the universe? There are so many fun and fascinating things to learn about space that the possibilities truly go to infinity and beyond. A great way start your child's educational space adventure is with this Real Life Sticker and Activity Book.

    Take a Walk on the Wild Side

    Biology class is in session! Here's your chance to get up close and personal with a great white shark without putting on a wetsuit. This 4D Great White Shark Anatomy Kit allows you to get an inside look at what makes these predators of the deep so powerful. And then take an even deeper dive into a shark's world with I Am Shark.

    Take advantage of this time at home and find new ways to keep exploring the world around you.

American country music is also known as country western music. It has a very long history. It comes from the folk songs of immigrants (移民) from Britain.

 Country music uses simple music and words to express everyday feelings such as loneliness, love, and sadness. That is to say, country music describes life. It talks about friends and enemies, trucks and roads, farm and crops. People in many parts of the world like country music, because everyone can understand what the music is about.

Country western music became popular first among cowboys (牛仔) in the American west countryside. Cowboys had to take care of cows day and night. When they were alone with the cows, they often sang beautiful and peaceful songs to calm the animals and to overcome their own fear. They were not well-educated and so they sang about their daily life in very simple words. They played guitars, violins and other instruments. In the south of America, many people added instruments from their homes, like bottles and spoons. When cowboys visited their friends and families on holidays like Thanksgiving, they usually sang and played country western music.  

In recent years, many musicians have made country western music a little different from the one in the past. These changes make the songs sound even better. Today singers such as Carth Brooks, Reba McEntire, Emmylou Harris, Lyle Lovett, Eddie Rabbitt, LeAnn Rimes, Randy Travis and a group called Alabama are singing and playing in different styles. They have brought country western music more and more fans from all over the world.