Where do the rivers starting from Zambia end?
SELECT DISTINCT ?uri WHERE { ?x <http://dbpedia.org/ontology/sourceCountry> <http://dbpedia.org/resource/Zambia> . ?x <http://dbpedia.org/ontology/riverMouth> ?uri  . ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/River>}
Zambia