Charles Ellicott Commentary Acts 21:37

"And as Paul was about to be brought into the castle, he saith unto the chief captain, May I say something unto thee? And he said, Dost thou know Greek?" — Acts 21:37 (ASV)

Can you speak Greek?—The chiliarch apparently expected his prisoner to have spoken Hebrew, i.e., Aramaic, and was surprised to hear Greek; the people expected Greek, and were surprised at Hebrew (Acts 22:2). Nothing could better illustrate the familiarity of the population of Jerusalem with both languages.