`29`. C every day
`=>` Dẫn chứng: dòng 1, 2. Every day on radio, on TV, and in the newsaper, we hear, see or read about many problems in the world.
`30`. D all are correct
`=>` Dẫn chứng: Dòng 4, 5. Air pollution mostly comes from fumes released from motorbikes, cars, airplanes, trains and poisonous gases emitted from factories.
`31`. A oil spills and factories wastes
`=>` Dẫn chứng: the sea has become so polluted from oil spills and factory wastes that the fish are dying.
`32`. A We should find a good solution.
`=>` Dẫn chứng: Dòng cuối. We must find a good solution that makes the world a better place to live.
