along用作副词的基本意思有二 ，一是“向前 ，往前 ”，常用在运动动词之后以加强其效果，二是“一道 ，一起 ” ，可用于人，也可用于物。用于美式英语还可指“接近” ，引申可指“在这里〔那里〕” 。along通常和动态动词搭配使用 。例句：Youmayhavetolearnafewnewskillsalongtheway。在这个过程中你可能还得新学几招。
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.