A horse is a useful animal和The horse is a useful animal

A horse is a useful animal和The horse is a useful animal ( )horse is ( )useful animal. 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 horse is an animal 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 老师讲的是 A horse is a useful animal,但是有一本教辅书上原句写的是 The horse is 1.The dog is a useful animal. the horse is a useful horse表示一类马,那可不可以the horses are useful The hourse is a useful animal.Horses are useful animal都是马是有用 改错：A fox is an useful animal.