Nancy's speech was very cogent.是什么意思？

Nancy's speech was very cogent.

南施的演说很有说服力.

speech

n. 演说，演讲，发言，说话，谈话，说话能力或方式，（乐器的）音，音色，方言，民族语言；

例句
The President declined to deliver the speech himself, on account of a sore throat...
总统因嗓子不适而婉拒了亲自讲话。

was

v. 用来表示某人或某物即主语本身，用来表示某人或某物属于某一群体或有某种性质（ be的过去式 ），在，存在，不受干扰；

例句
There was a terrible sadness in her eyes...
她眼神中流露出深深的悲伤。

very

adj. 很，非常，恰好是，正是，十足的，特有的；adv. 很，非常，充分，完全；

例句
Most people have very little difficulty in seeing why a Van Gogh is a work of genius.
多数人不难理解为什么凡·高的作品是天才之作。

cogent

adj. （理由、论据）有说服力的，令人信服的；

例句
There were perfectly cogent reasons why Julian Cavendish should be told of the Major's impending return.
要将少校即将返回的消息告知朱利安·卡文迪什是有绝对充足的理由的。