It is not a secret {#blank#}1{#/blank#} trees are vital to our life. They provide us with food, wood and most {#blank#}2{#/blank#} (important), oxygen. Now there is one more thing we can add to this list—blocking out harmful bacteria from water.

    The discovery {#blank#}3{#/blank#} (make) by a team {#blank#}4{#/blank#} (consist) of scientists from the Massachusetts Institute of Technology (MIT) and high school students {#blank#}5{#/blank#} were seeking a natural water filter(过滤)—one that would help communities in developing countries that do not have {#blank#}6{#/blank#} (accessible) to modern water filter systems.

    The {#blank#}7{#/blank#} (research), led by Professor Rohit Karnik, decided to turn{#blank#}8{#/blank#} trees for help, because they could allow liquid to flow through, while blocking out air bubbles.

    They began by cutting 1.5-inch-wide sections of tree bark from the branches of a white pine tree. The people related then tested the wood's filtering ability by pouring water containing red dye particles of different sizes through. To their {#blank#}9{#/blank#} (amaze), they found that it was effective in trapping all the particles. Greatly {#blank#}10{#/blank#} (encourage), the team conducted another experiment, this time with water that contained bacteria. Sure enough, the sapwood held back 99% of the bacteria, allowing only 1% to flow through.

    One of my fondest {#blank#}1{#/blank#}(memory) as a child is going to the river and sitting on the bank. There I would watch the bamboo trees bend{#blank#}2{#/blank#} the pressure from the wind and then watch them return {#blank#}3{#/blank#}(elegant) to their original position when the wind{#blank#}4{#/blank#}(die) down.

    When I think about the bamboo trees' ability {#blank#}5{#/blank#}(return) to its original position, the word “resilience (适应力)'' comes to mind. Have you ever felt like you were at your breaking point? Life is {#blank#}6{#/blank#} mixture of good times and bad times, and happy moments and unhappy moments. Always keep{#blank#}7{#/blank#} in mind that a measure of hope will take you through the unpleasant situation. With hope for a better tomorrow, things may not be as bad as they seem to be. The unpleasant situation may be much {#blank#}8{#/blank#}(easy) to deal with if the result is worth{#blank#}9{#/blank#}(have).

    The next time you are experiencing one of bad times or unhappy moments,{#blank#}10{#/blank#} take you close to your breaking point, bend but don't break!

    Recently Lindsay hasn't felt herself. She{#blank#}1{#/blank#}(be) a really good student, but her grades has fallen since three months ago. This is because she sometimes has trouble {#blank#}2{#/blank#}(pay)attention to her study. She also refuses to talk with teachers and friends. What's worse, she feels{#blank#}3{#/blank#}(tire) all the time but has difficulty in falling asleep.{#blank#}4{#/blank#}she does is brought to her mother's attention.{#blank#}5{#/blank#}, when her mother asks her what happens to her, she just says she feels like {#blank#}6{#/blank#}(cry).

    As a matter of fact, Lindsay is suffering {#blank#}7{#/blank#}clinical depression(临床抑郁症). What is clinical depression? It can be described as a mood which is so low that affects your everyday life{#blank#}8{#/blank#}(serious). The first sighs of it in teens are {#blank#}9{#/blank#}(poor) school reports than before, then learning difficulties and staying away from classmates and teachers. If you have these signs, don't worry. It is not so difficult to deal with clinical depression. There are many effective ways, such as medicine,{#blank#}10{#/blank#} (express) of feelings, more exercise and a balanced diet.

    The first UN Chinese Language Day {#blank#}1{#/blank#} (observe) on Friday at UN Headquarters in New  York in 2010. {#blank#}2{#/blank#} the world's most widely spoken language, it seems appropriate that Mandarin (普通话) has one day every year dedicated (把…专用于) to it. This {#blank#}3{#/blank#} (official) marked day of Mandarin language celebration was set by the United Nations as a way of celebrating the language's history and {#blank#}4{#/blank#} (contribute) to the world. It is hoped that having one day every year {#blank#}5{#/blank#} (celebrate) Mandarin will encourage more people around the world to take it up. With China likely to become the {#blank#}6{#/blank#} (large) economy in the world, it is important that the wider world becomes interestingly more perfect in this wonderful language. Every year UN Chinese Language Day {#blank#}7{#/blank#} ( fall) on April 20. A great way to get {#blank#}8{#/blank#} (involve) in the celebration is to join a Mandarin class or attend one of the many Confucius Institutes (孔子学院){#blank#}9{#/blank#} are set up in countries around the world. The number of people learning Chinese is on {#blank#}10{#/blank#} increase in China's neighboring countries, such as Korea, Japan, and Vietnam.

    As we all know, the Great Wall of China is one of the greatest {#blank#}1{#/blank#} (sight) in the world—the longest wall in the world ,which {#blank#}2{#/blank#} (consider) the symbol of China and the wisdom of Chinese people.

    With {#blank#}3{#/blank#} long history of more than 2300 years, the "Long Wall" was built in different areas by different dynasties {#blank#}4{#/blank#} (protect) their territorial (领土的) borders. During the construction of the Great Wall, there were many {#blank#}5{#/blank#} (interest) legends and stories, such as Meng Jiang Nü weeping over the Great Wall, a sad {#blank#}6{#/blank#} romantic love story.

    Today, the Great Wall has become a place {#blank#}7{#/blank#} interest not only to the Chinese but also to people all over the world. Perhaps the most {#blank#}8{#/blank#} (wide) famous advertising words in history come from the poetic pen of Chairman Mao: "He {#blank#}9{#/blank#} has never been to the Great Wall is not a true man," Actually, since the Great Wall was opened to the public, hundreds of millions of visitors {#blank#}10{#/blank#} (be) to its various sections.

    Spend four days enjoying the unique Spanish and local Indian culture high{#blank#}1{#/blank#}the Andes Cusco, the capital of the Inca Empire{#blank#}2{#/blank#}13th until the 16th century. Stay{#blank#}3{#/blank#}a local hotel, visit the museums, admire architecture, enjoy the excellent local food and go shopping{#blank#}4{#/blank#}the local markets.

    Enjoy the beautiful countryside{#blank#}5{#/blank#}you spend a day driving along the new highway connecting Cusco{#blank#}6{#/blank#}Lake Titicaca. There, the boat will take you to stay with a local Uros family{#blank#}7{#/blank#}an island{#blank#}8{#/blank#}three days. Both the island and the Uros homes are made{#blank#}9{#/blank#}water plants{#blank#}10{#/blank#}the lake.