Question: Who was the student of Democritus?
Paraphrase: Who was the understudy of Democritus?
SPARQL (Wikidata):  select distinct ?obj where { wd:Q41980 wdt:P802 ?obj . ?obj wdt:P31 wd:Q5 } 
Answer: Protagoras, Anaxarchus, Metrodorus of Chios, Nessas of Chios, Hippocrates