Question: What is the currency of the country whose national anthem is "Du Gamla, Du Fria"?
Answer(s):
answer: Swedish krona

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ?c)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
?c ns:location.country.national_anthem ?k .
?k ns:government.national_anthem_of_a_country.anthem ns:m.0m6w8 . 
?c ns:location.country.currency_used ?x .
}