Question: Who served as Vice-President under the author of "State of the Union Addresses of William J. Clinton"?
Answer(s):
answer: Al Gore

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:book.author.book_editions_published ns:m.04vs2vl . 
?c ns:government.us_president.vice_president ?x .
}