Question: What drugs were found in the system of the actress who starred in Whitney Houston: The Greatest Hits when she passed away?
Answer(s):
answer: Cocaine overdose

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:film.actor.film ?k .
?k ns:film.performance.film ns:m.0crrlzl . 
?c ns:people.deceased_person.cause_of_death ?x .
?x ns:people.cause_of_death.parent_cause_of_death ns:m.01tf_6 .
}