Question: Who served as Nixon's vp until 1975-11-20?
Answer(s):
answer: Gerald Ford

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.06c97)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.06c97 ns:government.us_president.vice_president ?x .
?x ns:government.political_appointer.appointees ?c .
?c ns:government.government_position_held.to "1975-11-20"^^xsd:dateTime . 
}