What are the county seats of the region which operates the Boeing Field?
SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/Boeing_Field> <http://dbpedia.org/ontology/operator> ?x . ?x <http://dbpedia.org/ontology/countySeat> ?uri  . ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Region>}
Boeing_Field