24. Air pollution occurs when wastes dirty the air. People produce most of the (1) ________ that cause air pollution. Such wastes can be in the form of gases or particles of solid or (2) ________matter. These substances result chiefly form burning (3) ________ to power motor vehicles and to heat buildings. Industrial processes and the (4) ________ of garbage also contribute to air pollution, Natural pollutants (impurities) include dust, pollen, soil particles and (5) ________ occurring gases. The rapid growth of population and (6) ________ and the increasing use of automobiles and airplanes have made air pollution a (7) ________ problem. The air we breathe has become so filled with pollutants that it can cause (8) ________ problems. Polluted air also (9) ________ plants, animals, building materials and fabrics, In addition, it causes (10) ________ by altering the earth’s atmosphere. 1. A. wastes B. products C. garbage D. subtances 2. A. tiny B. liquid C. organic D. volcanic 3. A. timber B. lead C. fuel D. carbon 4. A. disposing B. emitting C. contaminating D. burning 5. A. naturally B. unpleasantly C. odourlessly D. originally 6. A. industry B. electricity C. smog D. exhaust 7. A. harmless B. difficult C. poisonous D. serious 8. A. environment B. city C. atmosphere D. health 9. A. harms B. accounts for C. pollutes D. kills 10. A. pollution B. harmful gases C. damage D. volcanic eruption