Question: What countries share a border with the nation that includes an airport in Duisburg?
Answer(s):
answer: Belgium
answer: Czech Republic
answer: Luxembourg
answer: Netherlands
answer: Poland
answer: Switzerland
answer: France
answer: Austria
answer: Denmark

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:location.location.contains ?k .
?k ns:aviation.airport.serves ns:m.0ps1q . 
?c ns:location.location.adjoin_s ?y .
?y ns:location.adjoining_relationship.adjoins ?x .
?x ns:common.topic.notable_types ns:m.01mp .
}