1. Clean up one's act

自我检点，自我改进。

I should clean up my act. = I should improve myself.

我应该自我改进。

例子：She told him that if he didn't clean up his act and start looking for a job, she was going to leave him.

他告诉我要是他再不自我改进。并找一份工作，她就要离开他了。

2. Come down in buckets

倾盆大雨。

It is coming down in buckets.

正下着倾盆大雨。

例子：The road was flooded yesterday because the rain was coming down in buckets.

昨天下了一场倾盆大雨，路面都被淹了。

3. Cool your jets

冷静下来

You need to cool your jets. = You need to be less anxious, nervous, or excited.

你必须冷静下来。

例子：Cool your jets! The hotel is just around the bend and we will be there soon, so don't ask me again.

别着急，拐了弯就是旅馆。我们一会儿就到，所以你别在穷问了。