专业四级是针对英语专业同学的重要考试，其真题的参考价值无可比拟，希望同学们能够吃透真题，通过专四。
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"All large and medium-sized Chinese cities will have greater air quality monitoring by 2010." says a government official. The government has spent 150 million yuan on air quality monitoring systems across China since 2000 when officials began paying greater attention to air quality monitoring. More than 220 cities now have air quality monitoring systems and 42 others will have systems in place by the end of this year.