（1）录入：可以录入航班情况（数据可以存储在一个数据文件中，数据结构、具体数据自定） （2）查询：可以查询某个航线的情况（如，输入航班号，查询起降时间，起飞抵达城市，航班票价，票价折扣，确定航班是否满仓）；输入起飞抵达城市，查询飞机航班情况。 （3）订票：（订票情况可以存在一个数据文件中，结构自己设定）可以订票，如果该航班已经无票，可以提供相关可选择航班。 （4）退票： 可退票，退票后修改相关数据文件。((1) input: you can input flight conditions (data can be stored in a data file, data structure, specific data set) (2) query: you can query a route information (e.g., enter the flight number, check arrival and departure times, arrival departure city, flight fares, fare discounts, to determine whether the full flight warehouse); enter to take off from the city, check flight conditions. (3) booking: (booking data can exist in a data file, the structure itself set) can be bookings, if the flight has no ticket, can provide related optional flights. (4) refund: can be refunded, after the refund of the relevant data files.)