$2)$ St$.$ Pete Airlines has to keep track of its flight and airplane history. A flight is uniquely identified by the combination of a flight number and a date. In addition, every flight has a departure time and an arrival time. Every passenger who has flown on St$.$ Pete Airlines has a unique passenger number. The database should also store the name, address, and telephone number of each passenger. Clearly, a passenger may have taken many flights $($she must have taken at least one to be in the database$)$ and every flight has had many passengers on it$.$ For a particular passenger who has taken a particular flight, the company wants to keep track of the fare that she paid for it and the date that she made the reservation for it$.$ A pilot has an employee number $($unique$),$ name, date of birth, and date of hire. A flight has exactly one pilot. Each pilot has typically flown many flights but a pilot may be new to the company, can be in training, so has not flown any flights yet. Each airplane has a serial number $($unique$),$ model, manufacturer name, passenger capacity, and year built. A flight uses one airplane. Each airplane is used by many flights, but an airplane can be new and may not have been used at all. St$.$ Pete Airlines also wants to maintain data about its airplanes maintenance history. A maintenance procedure has a procedure number $($unique$),$ procedure name, and the frequency with which it is to be performed on every airplane. An airplane can be maintained many times, and a maintenance procedure can be applied to many airplanes. An airplane may be new and may not have been maintained at all. Also, a maintenance procedure may not have been applied to each airplane. When a maintenance procedure is applied on an airplane, St$.$ Pete Airlines wants to keep track of the date of the procedure, its location, and duration.