Air pollution
Pollution is the process of making something dirty. Sometimes, the air becomes dirty from (22)_____ causes. If a volcano erupts, it will fill the air with gases, pieces of ash and smoke. People often air to become (23) _____When garbage becomes old, a gas called methane fills the air. Cars fill the air with (24)_____.A lot of factories emit poisons into the air. Weapons of war add (25) _____gases into the air. To decrease air pollution, air quality standards, like the Clean Air Act, were enacted in 1963 and then some pollutants have been reduced.
21, A, natural D. natured B. nature C. naturally
22. A, take B. cause C. do D. put C. polluted
23. A to pollute B. pollution D. polluting
24. A fumes B. fumed C. fuming D. fumy
25. A. harmful B. deadly C. risky D. toxic
Pollution is the process of making something dirty. Sometimes, the air becomes dirty from (22)_____ causes. If a volcano erupts, it will fill the air with gases, pieces of ash and smoke. People often air to become (23) _____When garbage becomes old, a gas called methane fills the air. Cars fill the air with (24)_____.A lot of factories emit poisons into the air. Weapons of war add (25) _____gases into the air. To decrease air pollution, air quality standards, like the Clean Air Act, were enacted in 1963 and then some pollutants have been reduced.
22. A, take B. cause C. do D. put C. polluted
23. A to pollute B. pollution D. polluting
24. A fumes B. fumed C. fuming D. fumy
25. A. harmful B. deadly C. risky D. toxic