mell是闻的意思，rat指老鼠。这个谚语跟猫有关，据说猫即使是在看不见老鼠的状态下，也可以闻出躲藏在暗处的老鼠，而如果是人说I smell a rat，就是指虽然没有直接的证据或迹象显示出哪里有问题，但凭着自己的直觉，觉得有可疑的地方，现在一起来看看下面例句与相关的用法吧！
例：I smell a rat! Something’s not right with his story.
( 我觉得有鬼！他的说法一定有哪里不对劲。)
例：I smelt a rat when Noah offered to sell me the car at such a low price. That’s why I turned down his offer on the spot. It’s a good thing that I made the decision because the car turned out to be stolen.
( Noah 说要用很低的价钱卖车给我时，我觉得事有蹊跷，所以当场拒绝了他的提议。幸好我作了这样的决定，因为这部车原来是部赃车。)
另外fishy这个字也可以形容让人起疑的人事物，也就是suspicious的意思，再来看看两个例句吧！
例：It seems fishy that all the services here are free of charge.
( 这里的所有服务项目都免费，似乎有些可疑。)
例：The police became suspicious when they found out that he had lied about his whereabouts.
( 警方发现他对自己的去处撒了谎时，他们起了疑心。)
