The air surrounding us is important to everyone. Without air, we could not exist. Everyone understands that. But air is necessary in many other ways — ways that are not always so obvious or widely known.
If we did not have air, there would be no sound. Sound travels through air. Where there is no air, there is no sound. 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. The night time would be very cold and the days very hot. We would be forced to seek shelter from the sun, as there would be no atmosphere to protect us from the sun’s deadly rays.
In this huge ocean of air surrounding the earth, there is more energy than in all the coal, oil and gas we have on the earth. Electrical energy is collected in the atmosphere as water is collected and stored in a dam (大坝). The existence of electricity in the air has been known for centuries
A. air is important to human being
B. air is important to the earth
C. air is necessary in many other ways
D. air is necessary to the animals
| Air is all around us. It is around us
when we walk and play. From the moment we are born, air surrounds us. When we
sit down, it is around us. When we go to bed, air is also around us. No matter
where we are on earth, air surrounds us. We live in air. All living things need air. Living things cannot live without air. We can go without food or water for a few days, but we cannot live for more than a few minutes without air. When we are working or running, we need more air. So we breathe faster than usual. When we are asleep, we need less air. |
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