Can "si passivante" be constructed with null subject in certain contexts?

Question

Consider the following exchange in which si passivante appears:> A scuola, si leggono i libri?Surely a grammatical answer would be> Sì, si leggono i libri.If I wanted to not mention "i libri" again,which of the following answers would also be considered grammatical? 1. Sì, si leggono [subject ommitted] (si passivante) 2. Sì, li si legge. (si impersonale)The same problem occurs in the past tense:>Si sono letti i libri? 1. Sì, si sono letti. 2. Sì, li si è letti.Which of these are grammatical?

Answer 1

I do not undestand the question, when you say which of these are grammatical you mean grammatical correct? If so they are all correct!

Answer 2

The correct answer is: Sì, si leggono (i libri) in the present and Sì, si sono letti (i libri) in the past.

When the sentence contains a direct object si is passivante, not impersonale.