All living things need air. Living things can't live without air. We can go without food or water for a few days but we can't live for more than a few minutes without air. We take in air. When we are working or running, we need more air. When we are asleep, we need less air.
We live in air, but we can not see it.
We can only feel it. We can feel it when it is moving. Moving air is called wind. How can you make air move? Here is one way. Hold an open book in your hands in front of you. Close it quickly. What can you feel? What you feel is the air.
空气
空气包围着我们，当我们走路和玩耍的时候，它在我们周围。从我们诞生之日起，空气就在我们周围了。当我们坐下时，它在我们身边。我们生活在空气中。
所有生物都需要空气，没有空气生物就不能生存。没有水和食物，我们可以生存几天，但是没有空气几分钟我们都无法生存。我们吸进空气。当我们工作或跑步时，需要较多空气。当我们睡着时，需要的空气会少一些。
我们生活在空气中，但我们看不见它。
我们只能感觉到。当空气运行时，我们可以感觉到它。运动的空气形成风。你怎样使空气运动呢?有一种办法，手中拿一本展开的书放在面前，快速合上书，你能感觉到什么?你感觉到的就是空气。
