Question: Which of Richard Burton's wives died from heart failure?
Answer(s):
answer: Elizabeth Taylor

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.0cg9f)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.0cg9f ns:people.person.spouse_s ?y .
?y ns:people.marriage.spouse ?x .
?y ns:people.marriage.type_of_union ns:m.04ztj .
?x ns:people.deceased_person.cause_of_death ns:m.01l2m3 . 
}