أَزَيْدٌ قَامَ
Was it Zayd who stood?
Sometimes the action is already accepted, while its performer remains unknown. “A-Zaydun qāma?” can focus attention on whether Zayd, rather than someone else, was the one who stood.
Context can vary the interpretation of “A-qāma Zaydun?”, but fronting the person in “A-Zaydun qāma?” more overtly foregrounds the identity under question. Word order helps mark rhetorical focus.