Question: What NAFTA country has a nominal gdp currency of United States Dollar?
Answer(s):
answer: Mexico

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.05jj_)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.05jj_ ns:organization.membership_organization.members ?y .
?y ns:organization.organization_membership.member ?x .
?x ns:common.topic.notable_types ns:m.01mp .
?x ns:location.country.gdp_nominal ?c .
?c ns:measurement_unit.dated_money_value.currency ns:m.09nqf . 
}