用于实现航班的管理和查询，可以查询机票以及订票和退票。在查询的时候可以查询两个城市之间的最短航线，最少换乘航线以及经过某特定城市的最短航线，还能够实现动态显示的功能-Used to implement the flight management and query, you can check tickets and reservations and refunds. When the query can query the shortest route between two cities,