Question: Name the instrument used by scott joplin on the album If I Was A River?
Answer(s):
answer: Piano

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.07b69)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.07b69 ns:music.group_member.instruments_played ?x .
?x ns:music.genre.albums ns:m.012cf4dq . 
}