根据短文理解，选择正确答案。

    You may like chewing gum (口香糖) after meals to stop your breath smelling bad; or your mother might use a special neutralizer (调理剂) to protect her permed hair (烫发). But have you thought about the chemical principles behind such everyday actions?

    On March 2, the Senior 3 students from the IB (International Baccalaureate, 国际文凭) classes at Beijing Huijia Private School presented their discoveries, all in fluent English. This kind of seminar is held every year to show the achievements of the IB chemistry experiment lessons offered by the school. IB is a qualification based on a common curriculum (课程) for students aged 16-18 in any country and is recognized by universities everywhere.

    "Once I saw an advertisement for xylitol (木糖醇) gum," recalled Zhang Xinju. "Suddenly an idea came to my mind: are there any chemical reactions when the xylitol is working on our teeth?"

    Zhang and his partner Bu Xuan visited several hospitals to try and find out. "Doctors know that xylitol can protect teeth, but few could explain how the chemical reactions happen," said the 17-year-old boy.

    Presenting the results of their research in English to an audience of Chinese and foreign judges was never a problem for the students.

    "Textbooks for IB students are in English, and our teachers speak in English," explained Wei Duan and Han Yu, whose research topic was "The Acid-Base Reaction (酸碱反应) in the process of Hair-Perming".

    "In Senior 1 we often referred to Chinese textbooks, but we found we could understand and express it all in English by the second year."

    Lu Jiang, the school's IB chemistry teacher and China's only IB vice-examiner, is proud that her students can apply scientific theories they learn in class to daily life.

    "You might have learned these facts from you kindergarten teachers, but few think about the theories behind them," Lu said. "This kind of practice is intended to develop the scientific thinking they will need in their future studies."

    Are you interested in students in other countries: Do they also have so much homework like you?What do they do in their spare time?

    On April 8,a report came out on the lives of high school students in China,Japan,South Korea and the US.It surveyedaround 6,200 students from the four countries last year.You will find the answers to many of your questions in this report.

    Who study hardest?

    Chinese students spend the most time studying.Nearly half of Chinese students(48.6%) spend more than two hours on their homework every day.That's much more than students of the US(26.4%),Japan(8.2%) and South Korea (5.2%).

    Who sleep most often in class?

    Japanese students fall asleep in class most often.About 45% of them said they sometimes sleep in class.In South Korea,it's 32%;in the US,21%;and 5% in China.

    Who are the most distracted（分心的）?

    American students are the most active in class,but also the most distracted.64.2% said they chat with friends in class;46.9% said they eat snacks in class;and 38.9% said they send emails or read storybooks in class.

    What do they do after school?

    In their spare time,most Chinese students study or surf the Internet.Most American students go out to play with their friends.Most Japanese students do physical exercise.Most Korean students watch TV.

    Once upon a time there were two friends who lived in a palace and worked in the service of the king. One of the two boys knew a girl he liked so much that he wanted to give her a present.

    One day, when he was walking with his friend in the main palace hall, he saw a big vase filled with the most beautiful flowers. He decided to take one to give to the girl, thinking that no one would see him do so except his friend. He did the same thing the next day, and the next, and the next... until, one day, the king noticed how few flowers were left in the vase. He was so angry that he called everyone in the palace to come together in the hall.

    When they were all before the king, the boy thought he should say it was he who had taken the flowers. However, his friend told him to be quiet, because the king would be terribly angry with him. The boy was filled with fear, but when the king came near, he decided to confess.

    As soon as the boy said that he had done it, the king went red with anger, but on hearing what the boy had done with the flowers, a smile appeared on the king's face, and he said, “I couldn't have thought of a better use for my flowers.”

    And from that day, the boy and the king became great friends. They went to the vase and took two of those wonderful flowers, one for the girl, and the other for the queen.

    Rome wasn't built in a day, and the Internet didn't come out of a golden egg. Many of today's creations were not born of people who had creative ideas, but who did not stop at simply having an idea. They took one brick of capital (资本), another brick of knowledge, perhaps a brick or two of family and friends, and built their empires (帝国) brick by brick.

    If you want to build an online empire, you cannot settle for simply having a website full of articles, or a website full of pictures—there are already thousands of sites like that, so you need to come up with something new and creative.

    So if you are starting to build something up, ask yourself: what do you really want to do, and what are you really good at? Believe it or not, you can make money at something that you are an expert in, and you need to know what that is.

    Remember, having an online empire does not mean that you have to do it alone. You can take your friends along with you. Having a friend advertise your services online is a good way to attract more visitors to your empire.

    Building an online empire, you will have to be prepared to not only come up with creative ideas, but to carry your ideas through. Talk to people who have already succeeded in building their own empires. Talk to people who are struggling. Join a mailing list that will help you get through your struggle to achieve your goal.

    As you move forward, you will find that you can help other people, and you will have a good many stories to tell—not to mention a lot of money in the bank.

    If you learn the real secrets of creating a long term stable (稳定的) online business then you will have enough money to retire on.

    Why does time seem to fly by faster as we get old? You've got your aging brain to blame. This is likely due largely to the physical changes of our nerves and neurons (神经元). New research suggests 'rapid fire' abilities of the young brain allow us to process more information during youth, causing the days to seem longer earlier in life. However, as we get old, researchers say the older brain takes more time to process information.

    The new finding put forward by a Duke University researcher was published in a paper in the journal European Review this week According to Adrian Bejan, the J. A Jones Professor of Mechanical Engineering at Duke, the physical changes of our nerves and neurons play, a major role in our perception (知觉) of time as we get old. Over the years these structures become more complex and eventually begin to degrade.

    "Little babies, for example, move their eyes much more often than adults because they're processing images at a faster rate," Beian says, For older people, this means fewer images are being processed in the same amount of time, causing experiences to seem as though they're happening more quickly.

    Ray Tokuda, a 54-year-old Japanese American, is proud of the title his school has given him. He is a Shifu, a Chinese word literally meaning a master, mentor or senior practioner of martial arts.

    Tokuda has reason to be proud. He has been involved with Chinese martial arts for almost four decades. After learning them at the martial arts school in New Mexico State, today he is among the most experienced kung fu teachers of the school.

    Practicing martial arts two to three hours and helping students improve their skills have become Tokuda's daily routine. He expects to practice and teach martial arts for the rest of his life. "I'm still learning. It's worth more than a lifetime to learn Chinese martial arts," he said." Once I started, I just couldn't stop. I think it's also the magic of Chinese culture."

    Tokuda was sent to the martial arts school when he was 10. He still remembers how unwilling he was when starting out." My father had always wanted to learn Chinese martial arts but never got the chance, so he put his kid in," he said. "I was so afraid at that time because I thought kung fu was all about fighting."

    But things changed after he learned that martial arts were more than punching and kicking.

    "One of the things martial arts teach me is overcoming adversity," Tokuda said. "As a little kid, my first lesson was like, oh, look, this is a thing that I can get through by diligence, perseverance(毅力)and dedication, and that was priceless for my life."

    Learning Chinese martial arts opened a gateway for him to better understand Chinese culture because he could hear a lot of ancient Chinese kung fu-related stories. "It is like in America, where we hear stories about knights in shining armor and King Arthur and noble deeds done," he said. "I feel martial arts preserve something of ancient China that can't be found in books. They are sort of an oral history."

    Tokuda has also been invited to various events in his home state to showcase traditional Chinese culture, including the dragon dance and lion dance, which he also learnt at the martial arts school. Because of this, he is now considered a cultural envoy (使者) in the eyes of the public.