We don't use 'that' in non-defining relative clauses, so we must use 'which' When the pronoun refers to the thing, and 'who' if it refers to your person. We won't drop the relative pronoun in this type of clause, even if the relative pronoun is the object in the clause. https://edwinflgca.tusblogos.com/13098120/not-known-facts-about-contact-improvisation