query: SELECT ?country ?countryLabel ?lang ?capital ?capitalLabel
  WHERE {
    ?country wdt:P31 wd:Q6256 .
    ?country wdt:P37/wdt:P218 ?lang .
    ?country wdt:P36 ?capital .
    ?country rdfs:label ?countryLabel FILTER (LANG(?countryLabel) = ?lang) .
    ?capital rdfs:label ?capitalLabel FILTER (LANG(?capitalLabel) = ?lang) .
    FILTER (?countryLabel = ?capitalLabel) .
  }
  ORDER BY ?country ?lang