A house is a useful animal 翻译

改错：A fox is an useful animal. 1.The dog is a useful animal. an useful animal?还是a useful animal? A horse is a useful animal和The horse is a useful animal The hourse is a useful animal.Horses are useful animal都是马是有用 horses are useful animals/ a horse is a useful animal.马是有用的动 Everyone understands that （） horse is （） useful animal A a;a A horse is a useful animal 两处为什莫都用a a dog is a useful animal 的 a dog 要怎么解释为什么不是the dog 英语不定冠词,急A horse is a useful animal.这句话中为什么要在useful前加冠词,anima ( )horse is ( )useful animal. A cow is a useful animal这句话中的冠词是否错误