航空客运订票系统的业务活动包括：查询航线和客票预订的信息 客票预订和

办理退票等。设计一个计算机程序，使上述任务能借助计算机来完成。

-Air passenger reservation system' s business activities include: check routes and ticket reservation information such as ticket booking and obtain refunds. Design a computer program, so that these tasks can be accomplished using a computer.