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.

    Robert, a great golf player, once won a tournament. After {#blank#}1{#/blank#}(receive) the check, he walked a lot to his car in the parking lot and {#blank#}2{#/blank#}(approach) by a young woman.

    She congratulated him{#blank#}3{#/blank#}his victory and then told him that her child was{#blank#}4{#/blank#}(serious) ill and near death. She did not know how she could pay the doctor's bills. Touched by {#blank#}5{#/blank#}(she) story, Robert gave the check to the woman.

    The next week he {#blank#}6{#/blank#}have) lunch in a restaurant when a Professional Golf Association official came to his table. “The guard in the parking lot told me you met a young woman there after you won that tournament.” Robert nodded. “Well,” said the official, “I have{#blank#}7{#/blank#} piece of bad news for you. She's a {#blank#}8{#/blank#}(lie). She has no sick baby and she's not even{#blank#}9{#/blank#}marry). She cheated you, my friend.”

    “You mean there is no baby{#blank#}10{#/blank#}is dying?” said Robert.

    “That's right,” said the official.

    “That's the best news I've heard all this week.” Robert said.

    In much of Asia, especially the so-called"rice bowl" cultures of China, Japan, Korea{#blank#}1{#/blank#} Vietnam, food is usually eaten with chopsticks.

    Chopsticks are usually two long, thin pieces of wood or bamboo. They can also be made of plastic, animal bone or metal. Sometimes chopsticks are quite artistic. Truly elegant chopsticks might{#blank#}2{#/blank#}(make) of gold and silver with Chinese characters. Skilled workers also combine various hardwoods and metal{#blank#}3{#/blank#}create) special designs.

    The Chinese have used chopsticks for five thousand years. People probably cooked their food in large pots{#blank#}4{#/blank#}(use) twigs(树枝) to remove it. Over time,{#blank#}5{#/blank#} the population grew, people began cutting food into small pieces so it would cook more quickly. Food in small pieces could be eaten easily with twigs which {#blank#}6{#/blank#}( gradual) turned into chopsticks.

    Some people think that the great Chinese scholar Confucius{#blank#}7{#/blank#}lived from roughly 551 to 479 B.C. ,influenced the {#blank#}8{#/blank#}develop) of chopsticks. Confucius believed knives would remind people of killings and{#blank#}9{#/blank#}(be) too violent for use at the table.

    Chopsticks are not used everywhere in Asia. In India, for example, most people traditionally eat{#blank#}10{#/blank#} their hands.