IV. Choose the correct word marked A, B, or C to fill each blank in the following passage. People need to breathe. If they dont breathe, they (1)______ die. But how clean is the air people breathe? If they breathe (2)______ air, they will have breathing problems and become (3)_______. Plants and animals need (4)_______ air too. A lot of the things (5)______ our lives create harmful gases and (6)______ the air dirty, like cars, motorbikes, and factories. Dirty air is called (7)_______ air. Air pollution can also make our Earth warmer. The problem of air pollution started with the burning (8)_______ coal in homes and factories. 1. A. will B. are C. must 2. A. clean B. fresh C. dirty 3. A. well B. better C. ill 4. A. clean B. safe C. dirty 5. A. at B. in C. on 6. A. make B. get C. give 7. A. pollute B. polluted C. polluting 8. A. in B. for C. of