Question: What is the river whose source is Lake Ontario?
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:source <http://dbpedia.org/resource/Lake_Ontario>  . ?uri rdf:type onto:River}