Question: What insturments were used by the artist who headed the Hello Katy Tour?
Answer(s):
answer: Vocals

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:music.artist.concert_tours ns:m.05f95t7 . 
?c ns:music.artist.track_contributions ?y .
?y ns:music.track_contribution.role ?x .
}