Question: Which European sea has Oulu as one of the shore city ?
SPARQL:
SELECT DISTINCT ?uri WHERE {?uri <http://dbpedia.org/ontology/location> <http://dbpedia.org/resource/Europe> . ?uri <http://dbpedia.org/property/cities> <http://dbpedia.org/resource/Oulu>  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Sea>}