What is a recognized function of bāʾ in bi-muṣayṭir?

Supplementary Practice 28 — Comparative Rhetoric of Sūrat al-Aʿlā and Sūrat al-Ghāshiyah

• Reinforcement of negation, an emphatic bāʾ
• Bāʾ coordinates the nominal clause
• Taking it as an oath bāʾ
• Bāʾ marks a negative rhetorical question