all flights and fares from denver to pittsburgh on us air number 1039 on a thursday 
return flights ;return #1 from  denver ;return #2 to  pittsburgh ;return #3 on  us air number 1039 ;return #4 on  thursday ;return fares of  #5 ;return #5 ,   #6
['select', 'filter', 'filter', 'filter', 'filter', 'project', 'union']