Question: What is the allotrope of carbon that makes crystal that starts with letter C ?
Paraphrase: Name the carbon allotrope that forms crystal beginning with alphabet C.
SPARQL (Wikidata): SELECT DISTINCT ?sbj ?sbj_label WHERE { ?sbj wdt:P31 wd:Q622460 . ?sbj wdt:P1419 wd:Q895901 . ?sbj rdfs:label ?sbj_label . FILTER(STRSTARTS(lcase(?sbj_label), 'c')) . FILTER (lang(?sbj_label) = 'en') } LIMIT 25 
Answer: carbon nanotube, carbon nanotube