Most animals have little connection with animals of a different kind, unless they hunt them for food. Sometimes, however, two kinds of animals come together in a partnership (伙伴关系) which is good for both of them. You may have noticed some birds sitting on the backs of sheep. This is not because they want a ride, but because they find easy food in the parasites (寄生虫) on sheep. The sheep allow the birds to do so because they remove the cause of discomfort. So although they can manage without each other, they do better together.

    Sometimes an animal has a plant partner. The relationship develops until the two partners cannot manage without each other. This is so in the corals(珊瑚) of the sea. In their skins they have tiny plants which act as “dustmen”, taking some of the waste products from the coral and giving in return oxygen which the animal needs to breathe. If the plants are killed, or are even prevented from receiving light so that they cannot live normally, the corals will die.

    The guzheng is a traditional Chinese musical instrument. It belongs to the zither（齐特琴）family of string instruments. It is the parent of many musical instruments of some other countries.

    The guzheng should not be confused with the guqin, another ancient Chinese zither but without bridges. Now the guzheng is zither with movable bridges and usually 21 strings, although it can have from 15-25 strings. The guzheng's strings were formerly made of silk, though most players used metal strings by the 20^th century. Since the mid-20^th century most performers use steel strings. The guzheng has a large resonant cavity（共振腔）.

    The guzheng has existed since the Warring States Period and became especially popular during the Qin dynasty. The number of strings on the guzheng has always fluctuated. There were as few as 6 to as many as 23 strings during the Tang dynasty. The earliest record of the guzheng belonged to the historian Sima Qian. Until 1961, the common guzheng had 16 strings, although by the mid-20^th century 18-string guzheng were also in use. In 1961, Xu Zhenggao, together with Wang Xunzhi, introduced the first 21-string guzheng after two years of research and development. In 1960, they also invented the “S-shaped” left string rest, which was quickly adopted by all guzheng makers and is still used today. This curve allows for greater ease in tuning the strings and, combined with strings of different thickness, allows for greater resonance in both the deeper and the higher pitch（音调）ranges. The 21-string guzheng is the most commonly used one, but some traditional musicians still use the 16-string one.

    Good health is the most valuable thing a person can have but one cannot take good health for granted. It is important to remember that the body needs proper care in order to be healthy. There are three things that a person can do to help stay in good shape, eat right food, get enough sleep, and exercise regularly.

    Proper nutrition is important for good health. Your body cannot work well unless it receives the proper kind "fuel". Don't eat too much food with lots of sugar and fat, eat plenty of foods high in protein, like meat, fish, eggs and nuts. Vegetables and fruits are very important because they provide necessary vitamins and minerals. However, don't overeat It is not helpful to be overweight

    Getting the proper amount of sleep is also important. If you don't get enough sleep, you feel tired and easily get angry. You have no energy. Over a long period of time a little amount of sleep may even result in a change of personality(人的个性).Be sure to allow yourself from seven to nine hours of sleep each. If you do, your body will feel strong and refreshed, and your mind will be sharp.

    Finally, get plenty of exercise. Exercise firms the body, strengthens the muscles, and prevents you from gaining weight. It also improves your heart and lungs. If you follow a regular exercise program, you will probably increase your life-span(寿命). Any kind of exercise is good. Most sports are excellent for keeping the body in good shapes: basketball, swimming, bicycling, running and so on. Sports are not only good for your body, but they are enjoyable and interesting, too.

    If everybody were to eat the right foods, get plenty of sleep and exercise regularly, the world would be a happier and healthier place. We would all live to be much older and wiser.

    If you think you have two left feet but would love to be a good dancer then why not try your hand at dancing?

    That's exactly what I did five years ago and I immediately fell in love with dancing. To me, dancing is a magical experience: I've become fitter, look younger and feel more confident. I enjoy it so much that I will never give up this healthy pastime.

    It's very sociable as well. You meet people and make new friends while dancing the night away. Haven't you heard stories about how dancing inspired new romances or rekindled (重燃) old ones? My friends Joe and Rena just had their big day a few weeks ago after they met each other at a Ceroc workshop some three years before.

    The word “Ceroc” comes from the French language. Without the complicated footwork, it is easier to pick up by beginners. Another good thing about Ceroc is that while it is a partner dance, you don't have to bring a dancing partner.

    Other popular styles of dancing in the UK include ballroom, belly dancing, lindy hop, salsa, tango and tap dancing, just to name a few.

    No matter what types of dancing you do, one thing is for sure: you will become fitter. For office workers like me, dancing is good cardio exercise after a long day sitting in front of the computer screen. It also strengthens your muscles, improves your coordination(协调) and increases your physical confidence.

    Few people will end up being queens of the dance floor. The aim is not to win a competition but to enjoy the interaction(交流). As long as you do the right moves, keep the rhythm and most importantly keep an encouraging smile to your dancing partners, you will always be a winner!

    A new study shows students who write notes by hand during lectures perform better on exams than those who use laptops.

    Students are increasingly using laptops for note-taking because of speed and legibility(清晰度).But the research has found laptop users are less able to remember and apply the concepts they have been taught.

    Researchers performed experiments that aimed to find out whether using a laptop increased the tendency to make notes "mindlessly" by taking down word for word what the professors said

    In the first experiment, students were given either a laptop or pen and paper .They listened to the same lectures and were told to use their usual note-taking skills. Thirty minutes after the talk, they were examined on their ability to remember facts and on how well they understood concepts.

    The researchers found that laptop users took twice as many notes as those who wrote by hand. However, the typists performed worse at remembering and applying the concepts. Both groups scored similarly when it came to memorizing facts.

    The researchers' report said, "While more notes are beneficial, if the notes are taken mindlessly, as is more likely the case on a laptop, the benefit disappears."

    In another experiment aimed at testing long-term memory, students took notes as before but were tested a week after the lecture. This time, the students who wrote notes by hand performed significantly better on the exam.

    These two experiments suggest that handwritten notes are not only better for immediate learning and understanding, but that they also lead to superior revision in the future.

    Just what is a tiger mother？Amy Chua is a law professor at America's Yale University and her recent book on the subject is making waves. She's been called "dangerous", "outrageous", even a "monster" for her descriptions of how she brought up her two daughters.

    Her book Battle Hymn of the Tiger Mother describes fighting with a daughter for hours at the piano to ensure the child gets a piece of music right. She rejected birthday cards made for her by her girls because she didn't think they had made enough effort. She compared one child negatively with the other, threatening to burn their toys. Her rules include：schoolwork always comes first; an A ­ minus is a bad grade; children must be two years ahead of their classmates in math, and playing the violin or the piano is a must.

    Ms. Chua considers the Chinese hard work ethic(道德) as a way of creating happy, successful children—at least in her case. Although she's had a large amount of flak for her theories, one thing can't be ignored—the success of Chinese children in the education system.

    In Britain, shocking research shows that Chinese girls, for example, are outperforming all other foreign groups at GCSE—79 percent getting 5 A ­ C Grades, compared with 58 percent of white British girls. So what is it about Chinese parenting that's leading to high achievers？And how do Amy Chua's theories play into that success?

    She told me that if her daughter came back from school with 96/100 in a test, Chua would ask her what happened to the other 4 points. It's about always knowing "you can do better", she told me.

    Interestingly, in China, the birthplace of the tiger mother, people are moving away from traditional Chinese parenting. They are following more western parenting styles.