on the ball

有准备, 有把握, 警惕的, 能干的

例句与用法：

The new clerk is really on the ball. He's already improved the filling system in the office.

新来的办事员真能干，他已经改进了办公室文件归档的方法。

If you don't get on the ball and start studying harder, you're going to flunk.

如果你不积极进取，更加努力学习，你就会考不及格的。

The new publicity manager is really on the ball.

新的宣传部主任确实很内行。

The great value of Jack as a committee man is that he is always on the ball.

作为一名委员，杰克的巨大作用是始终保持警惕。

详细释义：

机灵的; 高明的; 勤奋的

This young man is on the ball: a good student and a good athlete.

这年轻人聪明又勤奋:是一位好学生也是一位好运动员。

That writer is really on the ball.

那位作家可真出色。