Perhaps you should try some spelling variations:
passiver » passiven, passively, passiert
passiverer » passivener, passivelyer, passierter, passiverwerb, passivieren, passieren
passioniert » passionierte, passionierter, passionierten
passivener » passiven, passiverwerb

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((passiver OR passive) OR ((passiverer OR passioniert) OR passivener)).
• Adding a wildcard symbol may retrieve word variants: ((passiver or passive) or ((passiverer or passioniert) or passivener))*.