Question: What zoo that opened on or before 2003 is a Houston Texas tourist attraction?
Answer(s):
answer: Houston Zoo

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.03l2n)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.03l2n ns:travel.travel_destination.tourist_attractions ?x .
?x ns:zoos.zoo.opened ?num .
FILTER (?num < "2003"^^xsd:dateTime) . 
}