Question: What airport is closest to the neighborhood of Harbourfront?
Answer(s):
answer: Billy Bishop Toronto City Airport
answer: Toronto Pearson International Airport

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.place_with_neighborhoods.neighborhoods ns:m.02kkt0 . 
?c ns:travel.travel_destination.how_to_get_here ?y .
?y ns:travel.transportation.transport_terminus ?x .
?y ns:travel.transportation.mode_of_transportation ns:m.025t3bg .
}