1.to lead a dog's life 形容人过着贫困潦倒、惨不忍睹的生活
Tom’s been leading a dog's life since he got divorced.
2.dog eat dog 残酷、竞争激烈
Some people say we live in a dog-eat-dog world.
3.work like a dog 指一个人努力、卖命地工作
They say that to be successful, a person has to work like a dog.
Such hard work can make him dog-tired.
5.sick as a dog 病得严重
The situation would be even worse if she became sick as a dog.
6.Every dog has its days.每个人都有属于自己的运气/每个人都有时来运转的一天
Don't give up and try your best I believe every dog has its day.
7.You can never teach an old dog new tricks. 老古董学不会新东西
You're never going to teach your father at the age of 79 to use a computer. You can't teach an old dog new tricks, you know.
8.meaner than a junkyard dog 冷漠，不友好
He is a man meaner than a junkyard dog.
9.His bark is worse than his bite. 刀子嘴、豆腐心
I wouldn't be scared of her if I were you. Her bark's a lot worse than her bite.
10.let sleeping dogs lie 不要自找麻烦、自讨苦吃
Green is trying to let sleeping dogs lie.
11.the dog days of summer 一年中最热的三伏天
I can do nothing except for swimming in the dog days of summer.
12.to rain cats and dogs 下倾盆大雨
In the middle of the picnic it started to rain cats and dogs, and everybody got soaked.