people need to breathe . if they don't breathe , they will die . but how (1)clean is the air people breathe ? if they breathe dirty air , they will have (2) breathing problems . plant and animal (3)need clean air too . a lot of the things in our lives create (4)harmful gases and make the air city ,like car , (5)motorbike, and factories . dirty air is called ''polluted air '' . air (6) pollution can also make our earth warmer .

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