如果形容一个人是 on the ball, 那就意味着这个人非常机灵。

例句

Brian managed to learn the new college computer system in just a couple of hours. He's really on the ball.

You have to be on the ball to win on that TV quiz show. You only have half a second to answer the questions.

请注意

如果形容某件事是 a whole new ball game, 那就意味着这是与以往不同的一种全新的事物。

I had a few Chinese lessons at school but actually speaking to Chinese people is a whole new ball game.