Task: Question Generation
Input (English): #1 return routes 
#2 return source airports of #1 
#3 return destination airports of #1 
#4 return where are #2 
#5 return where are #3 
#6 return #1 where #4 is in  the  United States 
#7 return #1 where #5 is in  the  United States 
#8 return #1 in  both #6 and  #7 
#9 return ids of #8
Output (English): Find the id of routes whose source and destination airports are in the United States.