What are some rivers in Zambia which have a dam on them?
SELECT DISTINCT ?uri WHERE { ?x <http://dbpedia.org/property/country> <http://dbpedia.org/resource/Zambia> . ?x <http://dbpedia.org/ontology/river> ?uri  . ?x <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Dam>}
Zambia