The hourse is a useful animal.Horses are useful animal都是马是有用

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 1.The dog is a useful animal. A horse is a useful animal和The horse is a useful animal an useful animal?还是a useful animal? the horse is a useful horse表示一类马,那可不可以the horses are useful ( )horse is ( )useful animal. Horses are a useful animal.这句话中的冠词a使用的对吗? 改错：A fox is an useful animal. The villagers don't know ____elephant is ____ useful animal. a dog is a useful animal 的 a dog 要怎么解释为什么不是the dog The elephant is _____ useful animal to human beings.A.a B.an