What is air? It has no colour, taste, smell or shape. We can't see it or smell it，but we can feel it. Air is everywhere. When the air moves, it becomes wind. The air moves quickly, and the wind blows strongly. The air moves slowly, and the wind blows gently. Air is important to all of us. People need it. Animals and plants need it. So we must keep the air clean and fresh. Don't smoke. Don't drive to school or the work place. You can take a bus or the underground. Of course, walking or riding a bike is the best. We can also plant trees or other plants to keep the air clean. Without air，we will all die. The dirty air is bad for our health. So let's try our best to keep the air clean.
