what is the {start time} for {Netherlands} has {head of government} as {Louis Beel} ?
Louis Beel became Prime Minister of the Netherlands when?
When did Louis Beel become Prime Minister of the Netherlands?
SELECT ?v WHERE { ?p property:head_of_government resource:Louis_Beel . resource:Netherlands property:head_of_government ?p . ?p property:start_time ?v }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q55> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P6> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q735519> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q55 p:P6 ?s . ?s ps:P6 wd:Q735519 . ?s pq:P580 ?value}