This is an useful tool.这个句子哪里错了?

This is an useful tool.这个句子哪里错了? useful,book,is,to,you,this连词成句 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 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 This is () useful story book.. 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? ( )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 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 an useful book.You'd better read it carefully.修改病句 This is an useful book .You must read it carefully .哪里错了? This is a ( ) useful advice A a B an C the D 应选哪一个急死了 this is useful advice to students of english应该是a piece of useful advice 难道 a piece of 可以省略 I think this is ____ useful dictionary.A.very a B.very an C.quite a D.quite an 几个选择,1、I think （）is very important to donate some money to the poorA、this B、it C、that D、he2、（）elephant is （）useful animalA、An；an B、An；a C、A；an D、A；a3、This programme is a（n）（）TV showA、lively This is _____ that all of us believe it’s very important.(2005年广州) A.such useful informationB.so useful an information C.so useful information D.such a useful information 给点建议 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