Air
     The air surrounding us is important to everyone. Without air, we could not exist. Everyone understands that. But air is ecessary in many other ways-- ways that are not always so obvious or widely known.
     For example, if we did not have air, there would be no sound, because sound travels through air. Without air there would be no fire. There would be no automobiles, since motors need air in order to operate.
     Without air, there would be no wind or clouds. There will be no weather. The night time would be very cold and the day time very hot. We woud be forced to seek shelter from the sun, as there would be no atmosphere to protect us from the sun's deadly rays.
     The atmosphere is all the air surrounding the earth. Atmospheric pressure is the weight of all the air against the surface of the earth. Many things on earth can not do without atmospheric pressure, as everyone knows. I won't give further examples.
In one word, we can not live without air.
[点评]
空气的重要性人人皆知，但它是怎么个重要法，并不是每个人都清楚，本文具体讲述了空气在人们不大注意方面的重要性。语句简洁、流畅。由于篇幅所限，结尾有些仓促。
[参考译文]
    空    气
    我们周围的空气对大家都很重要。没有空气，我们就无法生存。每个人都明白这一点。但是在很多其他方面——那些不大明显或不大为人所知的方面，空气也是必不可少的。
    比如，没有空气就没有声音，因为声音是通过空气传送的。没有空气也就没有火，也就没有汽车，因为汽车发动机需要空气来运转。
    没有空气就没有风，没有云，没有天气。夜晚会非常冷，白昼会非常热。我们会被迫寻找地方躲避阳光，因为没有大气层保护我们不受致命光束的侵害。
    大气就是环绕地球的空气。大气压则是所有空气对地球表面形成的重量。正如大家所知道的，地球上许多事情离开气压就无法实现。在此不再枚举。
一句话，离开空气，我们就无法生活。