Question: Name the river whose mouth mountain is Southend-on-Sea and mouth place is Essex?
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:mouthMountain <http://dbpedia.org/resource/Southend-on-Sea> . ?uri onto:mouthPlace <http://dbpedia.org/resource/Essex>  . ?uri rdf:type onto:River}