question: show me all the flights between dallas fort worth and either san francisco or oakland that depart between 5 and 7pm 
#1 return flights 
#2 return #1 between  dallas fort worth and  san francisco 
#3 return #1 between  dallas fort worth and  oakland 
#4 return #2 , #3 
#5 return #4 that  depart between  5 and  7pm