what is the {end time} for {Boeing} has {chief executive officer} as {William McPherson Allen} ?
What was the date that William McPherson left his position as CEO of Boeing?
When did William McPherson Allen step down as Boeing's CEO?
SELECT ?x WHERE { resource:Boeing property:chief_executive_officer ?s . ?s property:end_time ?x . ?s property:chief_executive_officer resource:William_McPherson_Allen }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q66> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P169> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q1493920> .
?statement <http://www.wikidata.org/entity/P582> ?value. 
} 

SELECT ?value WHERE { wd:Q66 p:P169 ?s . ?s ps:P169 wd:Q1493920 . ?s pq:P582 ?value}