【正确答案】Clean air is important to good health. If the air contains impurities, they may be absorbed by our bodies and make us ill. We need clean air, but unfortunately, air pollution is generally present, especially in cities. Our cities have many factories, which we need to make food products, clothing and many other things. Every day these factories pour millions upon millions of tons of smoke and soot into the air, which greatly pollutes the air. Nowadays, no area in the world is completely free of air pollution. We must take measures to control it.

【答案解析】 1.第二句中，要注意句内逻辑，翻译时可译为if条件状语从句。
   2.“吸收”可译为“absorb”。
   3.第三句中“目前普遍存在着空气污染”，意思是空气污染普遍存在，可译为“generally present”。
   4.第四句中，为了句子平衡，没有译为there be句型，而是将工厂的作用处理为非限制性定语从句，避免了“制造其他东西的工厂”与前两个在句式上的不一致。
   5.“排入……空气”译为了“pour...into the air”。
   6.“摆脱”译为“free of”。