March 20th is World Water Day every year. According to a report from the United Nations, more than half of the world's major rivers have serious water loss and are polluted.

    The Yellow River, the world's fifth longest river, watered some of the oldest farms on earth.

    {#blank#}1{#/blank#}Its source（源头）on Qinghai-Tibet Plateau is drying up. In most of the past 35 years, it didn't reach the sea.

    The Nile in Egypt, running 6, 650 km, is the longest river in the world.{#blank#}2{#/blank#}Now it is down to 2 billion m³ or so. Australia's Murray River reaches the sea only every other year. One fifth of America's Rio Grande has no water, either.

   {#blank#}3{#/blank#}

    Mostly it's damming（筑坝）and global warming that make rivers dry.{#blank#}4{#/blank#}Now about 45, 000 of them lie across the world's rivers. They hold back around 15% of the world's fresh water from running to the sea.

{#blank#}5{#/blank#}Warmer weather takes water away. The glacier（冰川）are becoming smaller. The source of the Yellow River is drying up because of it. Global warming has had certain effects on water sources. Droughts （干旱） happening around the world make people pay more attention to this fact.

    In the 13th century, the famous Italian traveler, Marco Polo, traveled a long way to China. During his stay in China, he saw many wonderful things. One of the things he discovered was that the Chinese used paper money. In Western countries, people did not use paper money until the 15th century. {#blank#}1{#/blank#}.

    A Chinese man called Cai Lun invented paper almost 2,000years ago. He made it from wood. {#blank#}2{#/blank#} He then put these pieces of paper together and made them into a book.

    {#blank#}3{#/blank#} We use a lot of paper every day. If we keep on wasting so much paper, there will not be any trees left on the earth. Every day, people throw away about 2,800 tons of paper. It takes 17 trees to make one ton of paper. This means that we are cutting nearly 48,000 trees every day.

    Since it takes more than 10 years for a tree to grow, we must start using less paper now. If we don't, we will not have enough time to grow more trees to take the place of those we use for paper.

    {#blank#}4{#/blank#} We can use both sides of every piece of paper, especially when we are making notes. We can choose drinks in bottles instead of those in paper packets. We can also use cotton handkerchiefs and not paper ones. When we go shopping, we can use fewer paper bags. If the shop assistant does give us a paper bag, we can save it and reuse it later.

    {#blank#}5{#/blank#} If we all think carefully, we can help protect trees. But we should do it now, before it is too late.

    Instead of studying abroad during college, more and more Chinese teenagers have chosen to do so as early as in high school, Students from China make up about 42 per-cent of the international students at high schools in the US, according to the latest study by the Institute of International Education. So, what is the main attraction for Chinese high school students to study abroad? What is overseas life like？We interviewed several students. Have a look!

    Pan. 15. Moreau Catholic High School in San Francisco, California, US

    In the future, I want to go to college in the US. Studying in high school here will help me get used to college life in the future. Also, I want to improve my English

    Studying here is not easy. Instead of exams like in China, we have more projects in class. For example, we have to make a PPT about a historical figure and then design a creative item for that person, such as a painting.

    Zhao. 15. Unionville High School in Toronto, Canada

    For me, experience matters. It's good to have the experience of living in another country. Unlike other international students, my parents accompanied me, which makes my life here much easier.

    In Canada. I have more time to develop my interests. I can choose classes I like.

    However, taking the entrance examinations to high school and college at home would be great. It's a shame that I have no chance to do that.

    Zheng. 14. Walsh Jesuit High School in Cleveland, Ohio. US

    I want to try different cultures and education styles. Two years ago, I visited some famous universities in Boston, such as Harvard and MIT. The academic atmosphere(学术氛围) deeply impressed me. Every student seems to spare no effort on academics. I saw students doing morning exercise everywhere and I watched a football game. I found that school life in the US was colorful. So I decided to study in the US.

    The villas(别墅)were very nice. Beautiful houses, wonderful lawns, and nice gardens. This was the kind of housing estate where John Wood preferred to work.

    It was just before eleven o'clock at night. After John drove around for the fifth time, he thought that he had found the right house-No. 4. There was no light and the garage(车库)door was open. John parked his car in the next street and then came into the garage.

    No one would think that a well-dressed gentleman with a white silk scarf and gloves, was really an excellent thief.

    After looking around the house for a while, John got down to work. He searched every room, and before long, his hands were full. He had two necklaces, some gold rings and a purse with a lot of money. He put all the things in his pocket.

    Then he found a small wall safe(保险箱)in the bedroom. John couldn't wait to take the valuable things from the safe and put them into his own pocket！But the thief met a problem; he couldn't open the safe.

    John wiped a few drops of sweat from his forehead, took off his gloves, and placed them on a chair. Again and again, and finally, he opened the safe. He saw something shining-a huge diamond.

    Suddenly, John heard someone opening the front door. It was the owner of the house. John put the diamond in his pocket, ran to the window, climbed out of the house and drove away in the dark.

    Ten minutes later, the police arrived. After searching the house. the police found an important piece of evidence(证据)that could easily tell who was the thief.

    Do you know what the piece of evidence was?