（1）Pollution is, in fact, threatening our existence.
（2）Villagers are as a rule healthier than people who live in towns. One reason for this is that country air is fresher than the air in smoky cities.
（3）Most of the noise in the city comes from traffic, factories and construction sites.
（4）There is an increasingly loud voice from the public calling for firm action against pollution.
（5）Scientists have warned that unless effective solutions are worked out, the problem of pollution will eventually get out of hand.
（6）Many factories discharge enormous harmful chemicals into air and rivers every day.www.yyzuowen.com
（7）To kill insects, farmers use a large amount of insecticides so as to have a bumper harvest. As a result, they pollute the air, water and land.
（8）The gas from car engines is very poisonous. It is a main source of air pollution in cities.
（9）Deforestation result in the increase of global temperature and unpleasant change of climate.
（10）The earth is our home and we have the duty to take care of it for ourselves and for our later generation.
（11）Beijing now has become one of the most polluted cities in the world. Among the 10 cities with the worst air pollution in the world last year, Beijing was the third most polluted city.
（12）If the city had not plagued by poor quality air, the annual death rate in Beijing would have been 4 percent lower in past three years, according to the research done jointly by Beijing Medical University and Harvard University.
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