What is the {train service} for {item operated} of {Amtrak}
Amtrak works which train administration?
Amtrak operates which train service?
SELECT DISTINCT ?b WHERE { resource:Amtrak property:item_operated ?b . ?b rdf:type ontology:train_service }
select distinct ?obj where { ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q23239> . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P121> . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj . ?obj <http://www.wikidata.org/entity/P31> <http://wikidata.dbpedia.org/resource/Q15141321> } 
 select distinct ?obj where { wd:Q23239 wdt:P121 ?obj . ?obj wdt:P31 wd:Q15141321 } 
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