Question: The character Troy Bolton and Darth Vader's voice are played by which actor?
Answer(s):
answer: Zac Efron
answer: Zac Efron
answer: Zac Efron

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.0f2y0)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.0f2y0 ns:film.film_character.portrayed_in_films ?y .
?y ns:film.performance.actor ?x .
?y ns:film.performance.special_performance_type ns:m.02nsjvf .
?x ns:film.actor.film ?c .
?c ns:film.performance.character ns:g.121cr_v1 . 
}