a dog is a useful animal 的 a dog 要怎么解释为什么不是the dog

The dog is (a/an/the//) useful any more A dog is a useful a_____ a dog is a useful animal 的 a dog 要怎么解释为什么不是the dog John Smith is (an) honest man.这里面为什么用an?The dog is (a) useful animal.这句里面为什么用a?最好详细一点, ( )useful book a/an an useful animal?还是a useful animal? A dog is a useful a______填空使句子更完整 A dictionary is an useful book.找错哪里错了? 改错：A fox is an useful animal.同题 I am an old dog.His a lucky dog.She is a lazy dog. useful前是加a还是an an ufesul还是a useful Dictionary is ______ useful tool.A an B a C / DDictionary is ______ useful tool.A anB aC /D the __ information it is Just put it into the computer .A How useful an B what useful C How useful D What a useful Eddie has_____e-dog,and____e-dog is very good.A.an;an B,the;an C,a;a D,an;the ______(Dog)dog is ______ useful animal. This is quite a useful book .解释一下quite为什么放在 a前面,useful是什么意思,为什么不定冠词不使用an? This is ______ useful book. A. a B. an C. the D/This is ______ useful book.A. a B. an C. the D/要解释