Question: Which key perosn of the Elders is also the president of united World College ?
SPARQL:
 SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/The_Elders_(organization)> <http://dbpedia.org/property/keyPeople> ?uri. <http://dbpedia.org/resource/United_World_Colleges> <http://dbpedia.org/ontology/president> ?uri}