4. Air Pollution

　　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.

　　5. Environmental Protection

　　Today the quality of our natural environment has become an important issue. The world population is rising so quickly that the world has become too crowded. We are using up our natural resources and at the same time polluting our environment with dangerous chemicals. If we continue to do this, life on earth cannot survive.

　　Concerned people have made some progress in environmental protection. Governments of many countries have established laws to protect the air, forests and sea resources and to stop environmental pollution.

　　Still more measures should be taken to solve environmental problems. People should be further educated to recognize the importance of the problems, to use modern methods of birth control, to conserve(保存) our natural resources and recycle(再循環(huán)) our products. We are sure that we can have a better and cleaner place in the future.

　　6. Automobiles

　　Automobiles, as a product of modern civilization, have been playing a vital part in the daily activities of human society. Industry needs automobiles for farming as well as transportation. Every day, automobiles drive people to and from work. On weekends automobiles take families for joyful outings. And during holiday seasons, automobiles fill the highways everywhere, even in remote areas. It could be said that the wheels of automobiles move society forward.

　　But automobiles have also given rise to a series of problems. For example, cities are overcrowded with automobiles. They create a lot of noise and traffic accidents which disable(傷殘) or kill many people each year. Worst of all perhaps is the air pollution caused by the exhaust gases produced by automobiles. Some of the gases are highly toxic(有毒的) and a serious health hazard.