China is the biggest market in the world, and many countries such as Germany, the USA, the UK and Russia do a lot of business in China. Let's have a look at some important tips to help you be successful when dealing with these nationalities.

    First, you must be punctual (准时的) with Germans. Even 5 minutes late makes a bad impression. Being punctual is also very important in the USA. In the UK, it's important to be punctual for business meetings, but nobody expects you to be on time for a social event. Half past seven really means a quarter to eight, or even eight o'clock! With Russians, you should always be on time, though it is not unusual for them to be one or even two hours late!

    It is best to dress formally and wear dark colours when you meet people from all the four countries. In Russia, designer clothes are very common. Don't be surpri if you go to an office in the UK on a Friday and find everyone wearing jeans. Many companies have “dress down Friday”, when people wear casual (随便的) clothes.

    In Germany, first names are only used by family members and close friends, so be prepared to use titles and last names. In the USA you will usually be invited to use first names almost immediately. The British are quite informal and using first names in business is more and more common, especially among younger people. In Russia, however, nobody uses first names, so use titles and last names.

    In conversation, the British and the Americans value humour, and both like to talk about sport. The weather is also a good topic of conversation with the British and the Americans, but avoid talking about politics. In Russia, say positive（肯定的） things about their country, but avoid making complaints. The Germans, however, prefer to get straight down to business!

    So, use these tips, and you will be on your way to a successful international business career!

    Unlike most other holidays, the history of April Fools' Day. Sometimes called All Fools' Day, is not as the totally clear. The only point in time that can be agreed on as the beginning of this tradition was 1582,in France. Before that year, the New Year was celebrated for eight days, beginning  on March 25.The reform of the calendar celetxration reached the highest point on April l_With the riform of the calendar under Charles 1X,the Gregorian calendar (公历, 阳历）was introduced, and New Year's Day was moved to January 1.

    However, because in those days communications were not as developed as they are today, many people did not receive the news for several years. Some people refused to accept the new calendar and continued to celebrate the New Year on April, These backward people were considered “foots” by other peopk. They were often sent on “fools” errands (徒劳无益的工作)or were made the taragets of jokes.

    This developed, over time, into a tradition of playing a trick on someone on the first day of April. The tradition eventully spread to England and Scotland in the eightreenth century. It was later introduced to the American colonies of both the Britain and Francc.April Fools' Day thus developed into an  international fun feast,so to speak,with different nationalities specializing in their own kind of humor at the expense of their friends and families.

    Have you ever spent an afternoon in the backyard, maybe grilling or enjoying a basketball game, when suddenly you notice that everything goes quiet? There is an old phrase "calm before the storm"， often used in a situation—a quiet period just before a great activity or excitement. According to our own experience, we know there is actually calm before the storm. But what causes this calm? And is it always calm before the storm? Let's hear what scientists have to say.

    A period of calm happens in a particular kind of storm, the simplest kind of storm—a single－cell thunderstorm. In this type of thunderstorm, there is usually only one main updraft, which is warm, damp air and drawn from places near the ground. Storms need warm and damp air as fuel, so they typically draw that air in from surrounding environment. Storms can draw in the air that fit their need from all directions—even from the direction in which the storm is traveling.

    As the warm, damp air is pulled into a storm system, it leaves a low－pressure vacuum(真空) coming after. The rising air meets the cold dry air that has already existed in the storm clouds, thus the temperature of the warm, damp air drops, and the water vapour (水蒸汽) in it changes into tiny drops that are a precondition of rain. These drops accumulate and build on larger particles like dust, until they grow large enough to form raindrops.

    This warm, damp air keeps moving upwards, but it becomes cooler and drier during its trip through cloud. When it reaches the top of the cloud, the air gets spit out(被挤出) at the top. This air is sent rolling out over the big thunderclouds. From there, the air goes down. Warm and dry air is relatively stable, and once it covers a region, that air, in turn, causes the calm before a storm.

    Most thunderstorms, though, don't start with calm. That's because most are actually groups of storms with complex wind patterns. There's so much air moving up and down storm groups that the calm before the storm never happens. Instead, before the storm, it might be really windy!

    Living in the wild can be hard. Finding food and staying safe aren't easy. Each day, animals try to survive in their habitats. Not all animals get by on their own. Some animals form a close partnership with other kinds of animals. These pairings are called symbiotic(共生的)relationships.

    In a symbiotic relationship, the animals depend on each other. One animal helps the other meet its needs. Sounds good, right? Not always. Some animals are not very kind to their partners. In some cases, one animal meets its needs but hurts its partner. Take ticks(扁虱), for example. These insects suck blood to live. To get blood, they attach themselves to other kinds of animals. Ticks can pass germs(细菌)that cause disease instead of helping their hosts.

    In other relationships, animals don't treat their partners so poorly. Both animals benefit from living with the other animal.

    Small animals called cleaner shrimps(清洁虾)have found a way of helping fish. As their name suggests, the shrimps clean the fish. They hang out at what scientists call a cleaning station. A fish stops by. Then a shrimp climbs onto the fish and even steps into the fish's mouth. The shrimp uses its tiny claws to pick stuff off the fish's body. That can include dead skin and tiny pieces of food that can hurt the fish. The fish gets a nice cleaning. The shrimp enjoys a tasty meal of fish trash.

    Small birds called plovers(灰斑)are also in the cleaning business. They have big customers-crocodiles. Crocodiles have long noses filled with sharp teeth. Cleaning them is funny. When a crocodile opens its mouth, the plover hops right in. It lets the plover eat small, harmful animals attached to the crocodile's teeth. The plover gets an easy meal while the crocodile gets clean teeth.

    A new study has found that social media could be affecting the sleep of young adults.

    The study is a project of researchers at the University of Pittsburgh's School of Medicine. They found that young people who often use social media are more likely to suffer from sleep disorders than those who use social media less. The researchers say doctors should ask young adults about their use of social media when treating sleep issues.

    "This is one of the first pieces of evidence that social media use really can influence your sleep." said Jessica C Levenson. She was the lead author of a report on the study.

    The researchers set out to examine the connection between social media use and sleep among young adults. Levenson noted that these young adults are possibly the first "generation to grow up with social media."

    The researchers wanted to find out how often young people used social media sites like Facebook, Twitter, Credit and Tumbler. For the study, they gave questionnaires to nearly 1,800 adults, aged 19 to 32. On average, members of the study group used social media sites one hour a day. They also "visited various social media 30 times per week."

    Thirty percent of the study's participants reported having serious problems with sleeping. Those people who used social media a lot were three times more likely to have a sleep disorder. And those who spent the most time on social media were two times as likely to suffer from sleep disturbances.

    Levenson said the number of times a person visits social media is a better predictor of sleep problems than overall time spent on social media. If this is true, she adds, then practices that stop such behaviors may be the most effective.

Soccer is played by millions of people all over the world, but there have only been few players who were truly great. How did these players get that way—was it through training and practice, or are great players "born, not made"?

First, these players came from places that have had famous stars in the past—players that a young boy can look up to and try to imitate (模仿). In the history of soccer, only seven countries have ever won the World Cup. There has never been a great national team—or a really great player—from North America or from Asia.

Second, these players have all had years of practice in the game. Pele, who is often named as the greatest soccer of all time, was the son of a soccer player. He began to play soccer with his father when he was only three. Most players begin playing the game at the age of three or four.

Finally, many great players come from the same kind of neighbourhood—a poor, crowded area where a boy's dream is not to be a doctor, lawyer, or businessman, but to become a rich, famous athlete or entertainer (艺人). For example, Liverpool, which produced the Beatles, had one of the best English soccer teams in recent years. Pele practiced in the street with a "ball" made of rags (破布). And George Best learned the tricks that made him famous by bouncing the ball off a wall (对着墙壁踢球) in the slums (贫民窟) of Belfast.

All great players have a lot in common, but that doesn't explain why they are great. Hundreds of boys played in those Brazilian streets, but only one became Pele. The greatest players are born with some unique quality that sets them apart from all the others.