Question: In which city is Air China headquartered?
SPARQL query:
PREFIX res: <http://dbpedia.org/resource/>
PREFIX yago: <http://dbpedia.org/class/yago/> 	
PREFIX onto: <http://dbpedia.org/ontology/> 
SELECT DISTINCT ?uri 
WHERE {
        res:Air_China onto:headquarter ?uri .
        ?uri rdf:type yago:City108524735 .
}