what is the {end time} for {W. M. Keck Observatory} has {significant event} as {construction} ?
When did the development of W.M. Keck Observatory finish?
When did the construction of W.M. Keck Observatory finish?
SELECT ?i WHERE { ?y property:end_time ?i . resource:W._M._Keck_Observatory property:significant_event ?y . ?y property:significant_event resource:construction }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q210997> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P793> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q385378> .
?statement <http://www.wikidata.org/entity/P582> ?value. 
} 

SELECT ?value WHERE { wd:Q210997 p:P793 ?s . ?s ps:P793 wd:Q385378 . ?s pq:P582 ?value}