Question: Which river's source place is Gloucestershire and mouth in North Sea?
SPARQL query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT ?uri WHERE {?uri onto:sourcePlace <http://dbpedia.org/resource/Gloucestershire> . ?uri onto:riverMouth <http://dbpedia.org/resource/North_Sea>  . ?uri rdf:type onto:River}