PREFIX   ex:  <http://example.org/>
PREFIX  rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs:  <http://www.w3.org/2000/01/rdf-schema#>

SELECT ?x ?c
WHERE { 
	?x rdf:type ex:Student . 
	?x rdf:type ?c .
	?c rdfs:subClassOf ex:Employee .
}
