8.4.1 exercise1: restrictive and non restrictive relative clauses
There are few languages where a distinction is to be made between restrictive and non restrictive relative clauses. Among the languages where this distinction exists are English and all the romance languages (That distinction doesn't exist for instance in German). If you already know the difference between a restrictive relative clause and a non restrictive relative clause in English you won't have any problems with that in Italian. As in English the non restrictive relative clause is separated from the main clause through commas and the relative pronoun quale can only be used in non restrictive relative clauses and even than only if the relative pronoun is the nominative inside the relative clause.
Decide whether the relative clause is restrictive or non restrictive. Instead of a possible comma there is a star.