Đề là chọn đáp án đúng : People need to breathe. If they don’t 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 clean air too. A lot of the things in our lives create harmful gases and (4) ____ the air dirty, like cars, motorbikes and factories. Dirty air is called “polluted air”. Air (5) _____ can also make our Earth warmer. The problem of air pollution started with the burning (6) ______ coal in homes and factories. 1. A. will B. are C. must D. can’t 2. A. clean B. fresh C. dirty D. good 3. A. well B. better C. ill D. strong 4. A. make B. get C. give D. help 5. A. pollution B. polluted C. unpolluted D. pollutions 6. A. in B. of C. on D. under