Question: In North America what countries has nominal gdp currency of the US dollar?
Answer(s):
answer: Dominican Republic
answer: Mexico

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.059g4)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.059g4 ns:base.locations.continents.countries_within ?x .
?x ns:location.country.gdp_nominal ?c .
?c ns:measurement_unit.dated_money_value.currency ns:m.09nqf . 
}