Zhè bù jìlùpiàn yāoqǐng le tèyuē gùwèn cānyù zhìzuò.
This documentary invited a special consultant to participate in its production.
Tips
usage
特约 is typically used as a modifier before a role: 特约记者 (special correspondent), 特约撰稿人 (contributing writer), 特约嘉宾 (special guest). It implies a non-staff engagement on a specific commission.