政府已经采取了一些积极措施：比如北京周边地区的空气质量在今年冬天大幅改善，这要归功于关闭污染企业并用天然气代替煤炭供暖。
The government has taken some positive steps: the air quality around Beijing, for example, has improved considerably this winter, thanks to efforts to shut down polluting factories and replace coal with natural gas for household heating.