Americans use many expressions with the word dog. People in the United States love their dogs and treat them well. They take their dogs for walks, let them play outside and give them good food and medical care. 【小题1】 The expression, to lead a dog's life, describes a person who has an unhappy existence.

【小题2】 That means many people are competing for the same things, like good jobs. They say that to be successful, a person has to work like a dog. This means they have to work very, very hard. Such hard work can make people dog-tired. And, the situation would be even worse if they became sick as a dog.

Still, people say every dog has its day. This means that every person enjoys a successful period during his or her life. To be successful, people often have to learn new skills. Yet, some people say that you can never teach an old dog new tricks. 【小题3】

【小题4】 People who are unkind or uncaring can be described as meaner(更吝啬的)than a junkyard dog. Junkyard dogs live in places where people throw away things they do not want. Mean dogs are often used to guard this property. They bark or attack people who try to enter the property. However, sometimes a person who appears to be mean and threatening is really not so bad. We say his bark is worse than his bite.

【小题5】 The dog days of summer are the hottest days of the year. A rainstorm may cool the weather. But we do not want it to rain too hard. We do not want it to rain cats and dogs.