The place was shaken (esaleuthē ho topos). By an earthquake most likely as in Act 16:26, but none the less a token of God’s presence and power (Psa 114:7; Isa 2:19, Isa 2:21; Heb 12:26.).
Were gathered together (ēsan sunēgmenoi). Periphrastic past perfect passive of sunagō.
They spake (elaloun). Imperfect active indicative, began to speak, after being filled (eplēsthēsan, aorist passive indicative) with the Holy Spirit. Luke uses the very words of the prayer in Act 4:29to describe their conduct.