what is the {end time} for {Beverly Sills} has {position held} as {chairperson} ?
On what date did Beverly Sills leave her position as chairperson?
When did Beverly Sills ended her position as a chairperson?
SELECT ?a WHERE { ?f property:position_held resource:chairperson . resource:Beverly_Sills property:position_held ?f . ?f property:end_time ?a }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q235517> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P39> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q140686> .
?statement <http://www.wikidata.org/entity/P582> ?value. 
} 

SELECT ?value WHERE { wd:Q235517 p:P39 ?s . ?s ps:P39 wd:Q140686 . ?s pq:P582 ?value}