Read the passage and fill in each gap with the most suitable word. Circle A, B, C or D. Air pollution, or dirty air, is (1)________ by many things. Great clouds of smoke come from (2)_______ chimneys. Cars (3)________ smoke and fumes into the air. Burning waste fills the air (4)_______ : bits of dirt. Even burning leaves (5)_______ smoke to the air. Smoke of all kinds is bad to (6)_______ and can do great harm to the body. (7)_______ countries have made laws (8) ________ limit the amount of fumes cars can exhaust into the air. (9)________ also set limits on pollution from power plants and factories. (10)________ scientists have not yet been (11)________ to stop air pollution, they have found ways to make cars and factories (12 )_____ fuel more cleanly. People are also more careful than they once (13) ______ . For example, they have stopped burning fallen leaves in the autumn. We still have a long way to go. (14)___________ if we all work together, we can (15) _________the problem. 1. A. causing B. caused C. inventing D. invented 2. A. factory B. factory's C. factories D. factories' 3. A. move B. pass C. push D. send 4. A. of B. on C. for D. with 5. A. produce B. producing C. add D. adding 6. A. breath B. breathing C. breathe D. breathed 7. A. Many B. A lot C. Some of D. A number 8. A. for B. on C. with D. to 9. A. We B. They C. Countries D. Nations 10. A. But B. Although C. However D. Yet 11. A. able B. ability C. enable D. enabling 12. A. fire B. set fire C. bum D. light 13.A. have B. have been C. been D. were 14. A. So B. So that C. But D. Because 15. A. solve B. finish C. move D. deal