Question: What is the tallest bridge that is also a railroad bridge?
Paraphrase: Of the railroad bridges, which is tallest?
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q1210334 . ?ent wdt:P2793 ?obj . ?ent wdt:P31 wd:Q1210334 } ORDER BY DESC(?obj)LIMIT 5 
Answer: Najiehe Railway Bridge, Qinglong Railway Bridge, Beipan River Shuibai Railway Bridge, Yachi Railway Bridge, Nanpan River Qiubei Bridge