what is the {start time} for {Carl Sagan} has {spouse} as {Ann Druyan} ?
What year did Carl Sagan marry Ann Druyan?
When was Carl Sagan married Ann Druyan?
SELECT ?a WHERE { ?m property:spouse resource:Ann_Druyan . resource:Carl_Sagan property:spouse ?m . ?m property:start_time ?a }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q410> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P26> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q27167> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q410 p:P26 ?s . ?s ps:P26 wd:Q27167 . ?s pq:P580 ?value}