this si an useful tool 错在哪?

this si an useful tool 错在哪? You should try your best to remember____from this class A.nothing useful B.useful somethingC.useful everything D.everything useful This is an useful tool.这个句子哪里错了? This is useful book.He wants to buy it at one.A,a quite B,quite a C,an quite D,quite an选哪个？为什么 useful,book,is,to,you,this连词成句 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 ( )elephant is ( )useful animal to p( )elephant is ( )useful animal to peopleA an,a B an,the C the,an D /,an回答时请适量说明原因 ( )useful book a/an Was this information useful? an outside room attached to a housezhong wen yi si? an useful animal?还是a useful animal? 英语翻译EFFICIENCYEfficiency of an artificial lift installation is the useful power transmitted to the produced fluid,divided by the power of the electrical energy being supplied to the prime mover.This definition applies to electric motor prime A horse is ( ) useful animal.A.an B.a C.the D.this This is ___ useful dictionary .选择：A.an B.a C.the D./ This is so useful an information that all of us believe it's very important. This is__ useful dictionary.填a还是an呢?答案上是a This is an useful book.You'd better read it carefully.修改病句