smell a rat 字面意思翻译为我闻到一只老鼠，记住千万不要这样翻译，这句话的意思是感觉什么事情不正常、奇怪、不对头的意思。用英语解释就是 feel that something is wrong。

He's been working late with her every night this week - I smell a rat!

他这周每天晚上都跟她工作到很晚，我觉得不对劲！

rat race 激烈的竞争；残酷、高压的生存环境

He decided to get out of the rat race, and went to work on a farm.

他决定摆脱这种高压的工作状态，去一个农场工作。

rat's nest 一团乱麻；乱作一团；乱得像猪窝

We just moved in, and the place is a rat's nest.

我们刚搬进去，这地方简直是个猪窝。