to wing it 即兴发挥（俚语）

英文释义

To do something without any planning or preparation.

例句

Usually I prepare for a speech carefully, but yesterday I was asked to speak at the conference without any warning, so I had to wing it.

我通常很认真地准备演讲，但昨天有人突然请我在会议上讲话，我只好即兴发挥。