a lucky dog 幸运者；
a big dog 大款；
a top dog 身居要职的人。
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。
汤姆自离婚后一直过着混沌潦倒的日子。
2.dog eat dog 残酷、竞争激烈
Some people say we live in a dog-eat-dog world。
有人说，我们生活在一个竞争激烈的世界。
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。
他们说，一个人想要成功就得拼命工作。
4.dog-tired 筋疲力尽
Such hard work can make him dog-tired。
如此坚辛的工作使他疲惫不堪。
5.sick as a dog 病得严重
The situation would be even worse if she became sick as a dog。
如果她病得厉害，情况会更糟。
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。
不要放弃，继续努力，我相信每个人都会有成功的时候。
