Rule reminder
Common errors in Italian cleft sentences include: wrong relative pronoun (using 'dove/quando' instead of 'che'), clitic resumption (incorrectly adding a clitic in the cleft relative clause), tense mismatch, agreement errors, and incorrect structure (omitting 'è' or 'che'). In cleft sentences ('È...che'), the relative clause NEVER contains a resuming clitic — unlike left dislocation. The copula agrees with the focus element in number.
Find the error: 'È Marco che l'ho visto ieri.'