How then shall they call? (pw oun epikaleswntai?). Deliberative subjunctive (first aorist middle) of epikaleomai (see verses Joel 1213 ). The antecedent of ei on (in whom) is not expressed. How shall they believe? (po pisteuswsin?). Deliberative subjunctive again (first aorist active of pisteuw just used). Each time Paul picks up the preceding verb and challenges that. Here again the antecedent ei touton before on is not expressed. How shall they hear? (po akouswsin?). Deliberative subjunctive (first aorist active of akouw). Without a preacher? (cwri khrussonto?). Preposition cwri with ablative singular masculine present active participle of khrussw, "without one preaching." How shall they preach? (pw khruxwsin?). Deliberative subjunctive again (first aorist active khrussw, to preach). Except they be sent? (ean mh apostalwsin?). Second aorist passive deliberative subjunctive of apostellw, to send, from which verb apostolo apostle comes. Negative condition of third class. In graphic style Paul has made a powerful plea for missions. It is just as true today as then.