Question: Name the gas that can cause formaldehyde exposure ?
Paraphrase: What gas causes a formaldehyde exposure?
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q21073026 . ?ent wdt:P2407 ?obj . ?ent wdt:P1542 wd:Q21174328 } ORDER BY DESC(?obj)LIMIT 5