Question: What is the river whose source region is North-Western Province, Zambia and river mouth is Indian Ocean?
SPARQL query: SELECT DISTINCT ?uri WHERE {?uri <http://dbpedia.org/property/sourceRegion> <http://dbpedia.org/resource/North-Western_Province,_Zambia> . ?uri <http://dbpedia.org/ontology/riverMouth> <http://dbpedia.org/resource/Indian_Ocean>  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/River>}
Answer: [Zambezi] is the river with North-Western Province, Zambia as a source region and mouth in the Indian Ocean.