These exercises require you to recognize and supply dative pronouns. You will use personal, reflexive, relative, and possessive pronouns, all in the dative case.
To help simplify things, note that the reflexive and personal pronouns are the same, except for the third person pronoun. The reflexive third person dative pronoun is sich, for all genders and numbers. Possessive pronouns follow the dative endings for ein, and relative pronouns follow the definite article endings, except for plurals. The dative plural relative pronoun is denen.