What is {position held} of {Alexander Dubček} that is {start time} is {1989-12-28} ?
On Dec 12, 1989 what was Alexander Dubcek's position?
What position did Alexander Dubcek hold on December 12, 1989?
SELECT ?k WHERE { FILTER ( CONTAINS ( YEAR ( ?z ) , '1989' ) ) . ?o property:start_time ?z . resource:Alexander_Dubček property:position_held ?o . ?o property:position_held ?k }
select distinct ?obj  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q150543> .
?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> ?obj .
?statement <http://www.wikidata.org/entity/P580> <1989-12-28>
} 

SELECT ?obj WHERE { wd:Q150543 p:P39 ?s . ?s ps:P39 ?obj . ?s pq:P580 ?x filter(contains(YEAR(?x),'1989')) }