Question: What was the operator of the London Underground that finished in December 31st, 1969?
Paraphrase: On December 31st, 1969, what was the factor of that completed the London Underground.
SPARQL (Wikidata): SELECT ?obj WHERE { wd:Q20075 p:P137 ?s . ?s ps:P137 ?obj . ?s pq:P582 ?x filter(contains(YEAR(?x),'1969')) }