Americans use many expressions with the word dog. People in the United States love their dogs and treat them well.
Some people say we live in a dog-eat-dog world. That means many people are competing for the same things, like good jobs. They say if a person wants to be successful he 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(手艺). They believe that older people do not like to learn new things and will not change the way they do things.
Dog expressions are also used to describe the weather. The dog days of summer are the hottest days of the year. A rain in summer may cool the weather. But we do not want it to rain too hard. We do not want it to rain cats and dogs.
【小题1】If a person without lots of money wants to buy a car, he or she has to ______.

　　Swimming is very popular in summer. People like swimming in summer because water makes them 1 cool. If you like swimming but swim in a 2 place, it may not safe. These years, more than ten people 3 while they were enjoying themselves in the water and 4 of them were students. But some people are 5 not careful in swimming. They often think they swim so 6 that nothing can happen to them in water. Summer is here again. If you go swimming in summer, don't forget 7 better swimmers have died in water. They died because they were not careful, not because they 8 swim. So don't get into water when you are alone. 9 there is a “No swimming” sign, don't get into water, 10 . If you remember these, swimming will be safer.