1. It's a real dog.

这是一条真狗？难不成还有假冒狗的？句子的字面意思确实如此。但事实上dog 在这里的意思是：something that they consider unsatisfactory or of poor quality 人们不满意或者觉得质量不好的东西。

所以这句话的真正意思是：这真是个不好的东西。也就是这个东西真不好。

例如：你去看了一场电影，你觉得电影太垃圾了，浪费了你的时间和电影票，这是你就可以说 The film is a real dog. 这个电影太糟糕了，真让人失望。

dog指不好的事的短语还有：

The economy is going to the dogs. 经济变得不好了。= The economy becomes worse.

可怜的狗

He lives in a dog's life. 他过着困难的生活。=He lives a hard life.

吃早餐的狗

The match was a dog's breakfast, and our coach was upset. 这场比赛打的很不好，我们的教练很失望。=The match was not good.

2. She's a lucky dog.

她是一只幸运的狗？从lucky “幸运的”来看，这应该是一句积极的话。没错，这里的dog意思是：a person who is regarded as lucky, unlucky, etc 一个幸运或不幸运的人。

所以这句话的真正意思是：她是一个幸运儿。她真幸运。

例如：她第一次去买彩票就中了大奖。这是我们就可以对她说 Wow. You are a lucky dog. 哇，你太幸运了。

dog指人的短语还有：

得意的狗

Every dog has its day. 人人皆有得意之时。

字面意思是：每个人都有属于自己的日子。引申一下就是说：三十年河东，三十年河西，别放弃，每个人都有自己说了算，自己做主的日子，也就是每个人都有成功的时候。也可以写成Every dog has his day. = Every person has his day.

懒狗

He is a lazy dog. 他真懒。=He is a lazy person. lazy 意思是懒的。

He is a top dog in his company. 他在他的公司是个名人。= He is very famous in his company. top意思是顶尖的，出名的

I tried to get my mother to start using a computer, but she says you can't teach an old dog new tricks. 老年人很难适应新事物。=You can't teach an old man new tricks. = An old man can't learn new things easily. tricks 意思是做事情的窍门。

狗咬狗

We live in a dog eat dog world. 我们生活在人吃人，竞争激烈的时代。= We live in a competitive world.