分别用use case diagram,sequence diagram,activity diagram 完成
Airline companies offer various flights.A flight is open to booking and closed again by order of the company.A customer can book several flights for different passengers.A booking is confirmed when there is availability for specified day,time,and flight number.A booking can be cancelled or confirmed by providing its reference number.A flight may involve stopover in cities.Customers can be provided with the option to book a hotel with their flight.