语法填空
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The world _______ (it) is becoming smaller and smaller with modern traffic, TV, telephone and so on. Life today is much easier _______ it was hundreds years ago, but it has also brought new problems. One of the biggest _______ is pollution. Pollution comes in many ways. We can see it, smell it, drink it and even hear it.
The more people, the more pollution. Many years ago, the problem was not so serious because there were not so many people. Man are_______ (pollute) the whole word now.
Air pollution is still the most serious. It’s bad to all living things in the world. Water pollution kills our fish and pollutes our drinking water. Noise pollution makes us angry more_______(easy).
Many countries are paying more and more attention ______   pollution . They make rules to stop people from_______(burn) coal(煤炭) in houses and factories in the city.
The pollution of CO2 is now the most dangerous problem of air pollution. It _____ (cause) by heavy traffic. It is sure that if there are ____ people driving, there ______(be) less air pollution.