Every form of the relative pronoun, including the ones that are easy to avoid.
Type the relative pronoun. The gender shown is the noun it refers to — the case comes from its job in the relative clause.
Subject (Nom) or direct object (Akk) of the relative clause.
After verbs like helfen, danken, gehören, gefallen, vertrauen — and for 'to whom'. The plural is denen, not den.
'Whose'. dessen for masculine and neuter, deren for feminine and plural — the noun after it doesn't change that.
The preposition decides the case, and it comes first: mit dem, für die, von denen.