以“Preserving Our Environment”为题，写一篇征文。要求按如下三条作为文章的提纲： 
　　1、人类正在污染环境。 
　　2、污染对人类的危害。 
　　3、如何保护环境。 
　　Preserving Our Environment 
　　Man is slowly polluting his environment. He dirties the air with waste gases； he poisons the water with chemical wastes； he damages the soil with fertilizers. 
　　Pollution does great harm to man. As we know， water， air and soil are necessary to man's survival. Polluted air， water and soil make people sick and even cause deaths. Environmental pollution is becoming one of the most serious problems that mankind faces. 
　　Now it's high time drastic action was taken. First， we should make the public aware of the dangers caused by pollution. Second， we should take pollution control measures to reduce pollution. Third， we should keep our pollution under control. After all， the earth is our home. We must take care of it for ourselves and our descendants.
Never miss deadlines. Never. 
　　Air Pollution 　　空气污染
　　Air pollution is one of the major problems of the modern world. A great deal of energy is needed to run the factories of modern industrial nations. Automobile, trains, planes and busses need energy, too. Nearly all of this energy is produced by burning fuels. The burning produces wastes, some of which remain in the air, causing air pollution. 
　　Scientists are finding ways to stop air pollution especially in big industrial areas and densely-populated cities. They are studying new ways of generating electricity that may be less damaging to the environment. In the meantime, many power plants are being modernized to give off less polluted material. Also, engineers try to design and locate new power plants to do minimum damage to the environment. 
　　However, it may be that we still have a long way to go before we have a "clean" world. Nearly all of the countries are trying hard to prevent and control air pollution. There indeed seems to be no end to tasks that environmentalists will be required to do. People will continually find new ways to control pollution.