卫生类英语概括大意（十二）

Air Transportation

　　Airplanes are used to carry passengers, cargo¹ and mail. Air transport companies operate scheduled airlines and non-scheduled services over local, regional, national, and international routes. The aircraft operated by these companies range from small single-engine planes to large multiengine jet transports.
　　The first air passenger services began in 1910, when dirigibles began operation between several German cities. The first scheduled airplane service to carry passengers began in the U.S in 1914. Several experimental airmail flights took place in India, Europe, and the United States before World War I, but air transport service did not become a true business until after the war.
　　During World War Two, intercontinental air transport became firmly established. After the war the new long-distance transports with advanced facilities were increasingly able to avoid storms and strong wind and make flights more economical and consistent. A new generation of "jumbo-jet" transports began operations in 1970, and the supersonic transport entered passenger service in 1976.