Declension patterns are used to use the right declension combos to any determiner and/or adjective preceding a noun. You need to use ‘der Junge’ to say ‘the boy in the nominative scenario after which use ‘den Jungen’ inside the accusative case. ‘Dem Jungen’ implies the dative situation. And ‘des Jungen’ https://web-hinweis.de/die-grundlagen-des-gesellschaftsrechts-den-rechtsrahmen-fur-unternehmen-verstehen/