Air is all around us. At the time we are born, air is around us everywhere(任何地方). We live in air.
All living things need air. Living things cannot live without（没有） air. We can go without food or water for a few days, but we can't live a few minutes without air. We take in air. When we are working, we need more air. When we are sleeping, we need less air.
We live in air but we cannot 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. Take an open book in your hands in front of your face. Close it quickly. What can you feel? It is air.
