Task: Question Generation
Input (English): #1 return flights 
#2 return #1 with  lufthansa 
#3 return #2 from  boston 
#4 return #2 to boston 
#5 return #3 to oakland 
#6 return #4 from  oakland 
#7 return #5 , #6
Output (English): does lufthansa fly between boston and oakland