【俚语】

Go to the dogs 大不如前，衰落
The employee can’t get paid and this company is going to the dogs.
这家公司的员工发不上工资，公司已经不行了。

Dog days 酷暑
I love to be in the swimming pool during the dog days of summer with friends.
在夏季酷暑的时候，我喜欢和朋友一起待在游泳池里。

Every dog has his day. 人人都有走运时
You may become famous someday. Every dog has his day.
你有一天可能就出名了。每个人都有走运的时候嘛。

Let sleeping dogs lie.
过去的事就让它过去吧

【例句】

Jill: Should I ask the boss if he's upset at my coming in late in the mornings?
我是不是应该问问老板，我早上迟到的事有没有让他不开心？
Jane: If he hasn't said anything about it, just let sleeping dogs lie.
如果他什么都没说，那就算了吧。

You can't teach an old dog new tricks.
你没法使守旧的人接受新事物

Good luck getting Grandpa to start going to yoga with you. You can't teach an old dog new tricks.
让爷爷去学瑜伽，我只能祝你好运了。你没法让他去学的。