1.Let sleeping dogs lie – do not make trouble if you don't have to.

不要自找麻烦

例句：There's absolutely no point pursuing this issue. We should just let sleeping dogs lie.

在这个问题上深究完全没有意义。我们不要自找麻烦了。

2.Not enough room to swing a cat – not enough space.

没有足够的空间

例句：You should see my new office, it's tiny. There's not enough room to swing a cat!(In old English, a cat was a whip not a real cat!)

你真应该看看我的新办公室。太小了。连转身的空间都没有。（在旧式英语里，cat是指鞭子而不是真的猫。）