He defended his viewpoint so eloquently that everyone present was convinced.

eloquently 是形容词 eloquent 的副词形式，由词根 loqu（说话）加上前缀 e-（向外）构成，字面意思是"能言善辩地"。eloquently 表示"雄辩地、有说服力地"，形容说话方式流畅有力、令人信服。