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咖啡酸具有止血功效,存在于多种中药中,其结构简式为.
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                                                                                        “能吞能吐”的森林
        森林涵养水源,保持水土,防止水旱灾害的作用非常大。据专家测算,一片10万亩面积的森林,相当于一个200万立方米的水库,这正如农谚所说的:“山上多栽树,等于修水库。雨多它能吞,雨少它能吐。”森林因这种特殊的“吞吐”功能而被科学家称之为“吞水吐雨器”。
        说起森林的功劳,那还多得很。它除了为人类提供木材及许多种生产生活的原料之外,在维护生态环境方面也是功劳卓著,它用另一种“能吞能吐”的特殊功能孕育了人类。因为地球在形成之初,大气中的二氧化碳含量很高,氧气很少,气温也高,生物是难以生存的。大约在四亿年前,海里的先进植物登陆,陆地才产生了森林。森林慢慢将大气中的二氧化碳吸收,同时吐出新鲜的氧气,调节气温,这才具备了人类生存的条件,地球上才最终有了人类。所以科学家又称森林是“吞碳吐氧机”。
        森林,是地球生态系统的主体,是大自然的总调度室,是地球的绿色之肺。森林维护地球生态环境这种“能吞能吐”的特殊功能是其他任何物体都不能取代的。因此,我们必须高度重视植树造林,并且保护好森林。目前,值得我们每个人关注的是地球的绿色之肺在日益萎缩。近200年间,地球上的森林已有三分之一以上被采伐和毁掉。而另一方面,由于地球上的燃烧物增多,二氧化碳的排放量在急剧增加。此消彼涨,使得地球生态环境急剧恶化,主要表现为全球气候变暖。全球气候变暖对人类的生产和生活有着巨大的影响,甚至威胁人类生存。因为全球气候变暖,水分蒸发加快,改变了气流的循环,使气候变化加剧,从而引发热浪、飓风、暴雨、洪涝及干旱。
        为了使地球的这个“能吞能吐”的绿色之肺恢复健康,以改善生态环境,抑制全球变暖,减少水旱等自然灾害,我们应该大力提倡植树造林,使每一座荒山都绿起来。

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    Are you a man or a mouse? When people ask this question they want to know whether you think you are a brave person or a coward(懦夫). But you will never really know the answer to this question 1you are tested in real life. Some people 2they are brave but when they come face to face with real danger, they act like cowards. Others consider themselves as cowards, but when they meet danger, they act like3.

    Lenny had always thought of himself as a 4person. He got worried before examinations. He worried about his job and his health. All he wanted in life was to be safe and healthy. Then, on January 15th, 2002, a plane crashed into the Potomac River in Washington. Lenny went to the river to see what was happening. He saw a woman in the ice-cold water. Lenny did not feel afraid. He kept very 5and did a very adventurous thing. He jumped into Potomac, swam to the woman, and kept her head above the water. Seventy-eight people died that day. Thanks to Lenny, it was not 6.

    When you are in a very dangerous situation and feel afraid, the body automatically (自动地) produces a chemical in the blood. This chemical is called adrenalin(肾上激素). With adrenalin in the blood system, you actually feel stronger and stronger and are ready to fight or7 However, when you are absolutely terrified, the body can produce too much adrenalin. When this 8 the muscles become very hard and you find you can't move at all. You are paralyzed(使无能为力) with fear. This is9 when we are very frightened, we sometimes say we are “petrified”. This word comes from a Greek word “petros”, which means “stone”. We are10 frightened that we become stonelike.