A、They are happy. B、They are friendly. C、They are angry. D、They are hungry. C短文指出，狗摇尾巴表达的是友好，而猫在生气的时候才会这样做。

　　If you have brothers and sisters, you know it’s completely natural for arguments to take place from time to time. Well, it doesn’t mean you don’t love each other, though; it just means you spend a lot of time together and it’s only natural to have disagreements. You may even hear parents say their kids "fight like cats and dogs." (23) "Fighting like cats and dogs" is a common phrase that people use to mean people argue, fight or don’t get along. If you like cartoons, you’ve probably seen many that portray cats and dogs fighting like sworn enemies. There have even been movies made that pit cats against dogs. With many questions in life, there’s simply no easy answer to the question of whether dogs and cats can get along. (24) Dogs and cats are different in many ways that can make it difficult for them to get along. (25)For example, both dogs and cats have tails, but tails can make things confusing. When a dog wags its tail, it’s sending a friendly message. Cats, however, wag their tails when they’re angry. You can see how this might lead cats and dogs to become confused if they’re facing each other with wagging tails! Although dogs and cats aren’t really natural mortal enemies, dogs are hunters by nature. This means that they might hunt and chase anything that moves, including a cat. This natural behavior could cause problems between dogs and cats. However, with patience and the right circumstances, cats and dogs can be best buds.
　　23. What do parents mean when they say their kids "fight like cats and dogs"?
　　24. Why do dogs and cats fight often?
　　25. What does it mean when cats wag their tails?