U.S. corp. regulators have approved the creation of the world's largest airline, a merge of two U.S. carriers, American Airlines and U.S. Airways. The airlines agree to give up some of their takeoff and landing rights at seven key airports in the U.S., mostly at one of three airports serving Washington. ____________________美国公司监管部门批准成立世界上最大的航空公司,这是由美国航空与全美航空两家公司合并组成的.这家航空公司同意在美国境内放弃七个关键航空港的起飞和降落权,其中主要有三个航空港为华盛顿提供服务._________________________