Question: Which country was the Vietnam war located that has Lao as its official language?
Answer(s):
answer: Laos

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.07_nf)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.07_nf ns:time.event.locations ?x .
?x ns:location.country.official_language ns:m.011ln5 . 
}