Question: What are the former team of the american football players who played at gridiron football position ?
SPARQL:
SELECT DISTINCT ?uri WHERE { ?x <http://dbpedia.org/property/position> <http://dbpedia.org/resource/Tackle_(gridiron_football_position)> . ?x <http://dbpedia.org/ontology/formerTeam> ?uri  . ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/AmericanFootballPlayer>}