Our earth has been threatened by all kinds of pollutions. Acid rain is a kind of air pollution which is hanging over our heads and coming down from many different 【S1】______ ways such as rain and snow. It damages forests, lake and 【S2】______ rivers, buildings and even human health. Several chemicals, including of sulfur dioxide, nitrogen 【S3】______ oxides and ozone, are involved in causing acid rain. These chemicals either come directly from power station chimneys and cars, and are formed from a 【S4】______ combination of pollutant gases. Sulfur dioxide is the one chemical what is often associated with acid rain. 【S5】______ It is mainly emitted by large coal burning power stations. It affect places thousands of miles away as 【S6】______ well as areas around the power stations. To prevent more or worse environmental effects from acid rain, 【S7】______ we have short-term and long-term solutions. We should 【S8】______ just clean up our power station chimneys and car exhausts. We should also change the way society thinks and reacts. We need to conserve energy by decreasing efficiency. 【S9】______ We also need to change our way of transport, that is, create a more efficient transport system which depends less on private cars and more a good public 【S10】______ transport network. Everybody should work together to save the world. 【S1】