Task: Question Generation
Input (English): #1 return flights 
#2 return #1 from  pittsburgh 
#3 return #2 to san francisco 
#4 return #3 thursday night 
#5 return #4 on  us air 
#6 return if  there  is  #5
Output (English): is there a thursday night flight from pittsburgh to san francisco on us air