en_tn/act/21/37.md

As Paul was about to be brought

This can be stated in active form. Alternate translation: "As the soldiers were ready to bring Paul" (See: rc://en/ta/man/jit/figs-activepassive)

the fortress

This fortress was connected to the outer temple court. See how you translated this in Acts 21:34.

the chief captain

a Roman military officer of about 600 soldiers

The captain said, "Do you know Greek?

The chief captain uses this questions to express surprise that Paul is not who he thought he was. Alternate translation: "So you know Greek." or "I didn't know you knew Greek." (See: rc://en/ta/man/jit/figs-rquestion)

know Greek

know how to speak and understand the Greek language