on the ball

[英语俚语]机智；谨慎；小心

The old man always works on the ball, and tries to do nothing wrong.

这个老头总是很谨慎，尽量不做错任何事情。

注解：
ball指球，to be on the ball意为站在球上，喻指留意，小心，以免摔下来。

chill out

[美俚]歇一会儿

You have been writing for three hours without chilling out for a while. Have you finished it?

你都写了三个小时了，也没歇会儿，你写完了吗？

注解：
chill意指寒气，寒冷；

to chill out系指冷却，喻指歇口气，松口气。