题目

With the development of industry， air pollution is getting more and more serious. In Shanghai, many people suffer from different kinds of illnesses because    61    air pollution.     Air pollution is    62   （main） caused by the following reasons. About half of the problem is caused by vehicles. There are more and more cars and buses on the road，   63    give off    64   （poison） gases. 35% of air pollution is caused by factories.    65    factor is the smokers.    66   （smoke）does harm to others’ health as well as to    67    (1)我国西北干旱、半干旱区油气资源丰富。西部大开发首先要[　　 ] A.发展高新产业，加快城市化进程 B.人口外迁，减轻环境压力 C.治水改土，改造低产田 D.抓好基础设施和生态环境建设 (2)“西气东输”的主要原因是[　　 ] A.西部资源开发成本低　　 B.东部市场需求量大 C.地势西高东低，便于管道输送 D.东部靠海，便于出口