Question: Sumy Oblast was a citizen of what country in 1991?
Paraphrase: What country was Sumy Oblast a citizen of in 1991?
SPARQL (Wikidata): SELECT ?obj WHERE { wd:Q170446 p:P17 ?s . ?s ps:P17 ?obj . ?s pq:P582 ?x filter(contains(YEAR(?x),'1991')) }