In the 13th century, Marco Polo,the world known Italian traveller, saw many wonderful things in China. One of the things he discovered was money made of paper. People in the West did not have such kind of money until the 15th century. However, the Chinese began to use it in the 7th century.

    Paper was invented by a Chinese man called Cai Lun almost 2,000 years ago. But it was not made in Europe until the year 1100. Four hundred years later, a German discovered that he could make the best paper from trees. After that countries rich in forests, such as Canada, Sweden, America, Finland, became the most important ones in paper making.

    Paper can be used in many ways. The common uses include newspapers, magazines and books. But do you know that paper can be used for keeping warm? In Finland, the farmers wear paper boots to keep their feet warm in the snow. And even houses can be insulated(使绝缘) from heat or cold with paper.

    However, we have to understand that paper still comes from trees now. If we keep on wasting so much paper, there will not be any trees left on the earth some day in the near future. Every day people throw away about 2,800 tons of paper in our city. It takes 17 trees to make one ton of paper. This means that we are cutting down nearly 48,000 trees every day. The fact is that it takes more than 10 years for a tree to grow.

    So we must start saving paper right now. We can use both sides of every piece of paper. We can make useful things out of used paper. We can use china cups instead of paper ones. When shopping, we can use fewer paper bags and reuse them if we have some.

    In short, we should keep a balance(平衡) between using paper and protecting trees, and do it now before it is too late.

    Exam time is the most stressful period of the year. You have worked all school term on your classes and now it's the time to prove what you have learned. With so much at stake (处于成败关头), it is easy to get stressed about your exams. However, with the right amount of hard work and focus you can pass your tests easily.

    When I was in school, I used to get very stressed over my exams. So did my friends. Some people stopped eating and others ate too much! Some gave up and others burned themselves out! The most important thing to remember when studying is not to feel frightened! Take the middle path -- stay calm, eat healthy and get a rest. Pushing yourself too hard is just as dangerous as not studying enough. A tired, overworked brain is just as useless as a lazy, empty one!

    So, what should you do ?Arrange a time each day for study and a time for relaxation .You may have less time to relax than usual, but you still need to let your brain rest for a few moments. Get plenty of sleep .If you are tired, information will not stick in our memory. Finally eat healthy foods that fuel （给……加油）your body and mind.

    It is bad to think too much about your exams. Some students may think that the rest of their life depends on them .That's not true. Instead, just view the exams as another difficulty you will overcome. You have overcome all kinds of difficulties in you life so far. With the right amount of work and focus, you will pass your exams with flying colours! High school is right around the corner!

    The Chinese tradition of giving gifts of money in red envelopes at Lunar New Year has turned into big business for Web giants Alibaba and Tencent, which now both offer electronic "hong bao".

         At the end of each lunar year, it is common in China to give children hong bao — some money in envelopes that are red, the colour of success. But now the old also take part in this activity.

    It is now possible to exchange "red envelopes" with smart phone, which is popular in China and has caused a battle(战争) for the lucrative market between the two companies providing the service, Tencent and Alibaba.

         "You don't have to pay the same cost or wait as long as you would for a traditional bank transfer(转账). It's more convenient, simple and fun," Wang Le, a 28-year-old Beijinger, told AFP. " With electronic red envelopes, you're not limited by your identity（身份） or the time of year. It's a new, fresh way of playing the game."

    The idea was introduced in 2014 by WeChat, a mobile messaging system with over 400 million users and run by Tencent, China's largest Internet service system. It was successful at once.

    This year, Alipay Wallet（阿里支付宝）, the payment system run by Alibaba, is ready to take on the competition. It is allowing its 190 million users to send digital gifts, especially on the Twitter-like Sina Weibo.

    For the past few weeks a digital battle has been terrible, with Tencent banning （禁止）Alipay from sending red envelopes on WeChat, saying they were at a risk. Recently, WeChat also blocked(封锁) Alibaba's music app Xiami.

    To attract the public's attention, the two companies have launched lotteries through which they award red envelopes to users in an online game.

     It's easy to send and receive hong bao or take part in the lotteries: you simply need to register （登记）your bank details.

     According to market research group iResearch, Alipay controls 82.6 percent of the Chinese mobile phone payment market, compared to 10 percent for Tencent's Tenpay.