题目：设有一航班售票系统，要求完成以下功能： 1）假设该民航有若干航班，要求实现增加航班和取消某个航班的功能。 2）查询：根据用户提出的终到站查询航班号...

题目：设有一航班售票系统，要求完成以下功能： 1）假设该民航有若干航班，要求实现增加航班和取消某个航班的功能。 2）查询：根据用户提出的终到站查询航班号、售票情况等航班信息；也可根据航班号，列出该航班已订票的乘客名单。 3）订票：根据航班号为客户订票，如该航班有余票，则为客户订票；如该航班已满员，则显示相应信息。 4）退票：按乘客要求退出已预定的机票。 -Topic: First flight with the ticketing system, required to complete the following functions: 1) It is assumed that the Civil Aviation have a number of flights, calls for increased flights and cancellation of a flight functions. 2) query: Based on user queries raised by the end of the arrival flight number, booking flight information, etc. also available under the flight number, listed in the flight