22.214.171.124 relative pronouns with and without prepositions
A preposition is something like that
We talked about that problem.
And a relative pronoun with a preposition is something like that
The problem about which we talked is no resolved.
Without preposition we have in Italian the relative pronouns che, chi, il quale / la quale / i quali / le quali. But without prepositions normally che is used. The other prepositions are rarely used without prepositions. We will discuss their use later on.