Was reading (ανεγινωσκεν). Imperfect active descriptive, not periphrastic like the two preceding verbs (was returning and sitting). He was reading aloud as Philip "heard him reading" (ηκουσεν αυτον αναγινωσκοντος), a common practice among orientals. He had probably purchased this roll of Isaiah in Jerusalem and was reading the LXX Greek text. See imperfect again in verse Acts 8:32.