Auxilliary (helping) verb: Ich bin/habe + Partizip II (Partizip Perfekt) – e.g. gefahren/gekocht ( I travelled/I cooked) 1. Auxilliary verbs are: HABEN (used to form Perfekt) SEIN (used to form Perfekt, Passiv) WERDEN (used to form Futur, Passiv) ...
Useful links: German Cases: A Complete Guide (clozemaster.com) German Cases Simply Explained: A Guide to German Cases (lingopie.com) Learn how to say German numbers (with audio) (thegermanproject.com)