This is _most useful reference book I have on this subject.

This is _most useful reference book I have on this subject. This is () useful story book.. This is useful work改为否定句 This is useful work改为一般疑问句 This is （ ） useful book．（填冠词） This is the _______ useful of the four books.(little) useful,book,is,to,you,this连词成句 This is an useful tool.这个句子哪里错了? Was this information useful? This is a useful dictionary. So it is,and it is ______unusual one. 添什么,为什么 This is that we all think it's very important.A such useful information B so useful information 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 advice to students of english应该是a piece of useful advice 难道 a piece of 可以省略 this is the ____(useful) book l bought in this bookstore. 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 （）interesting book and it is also （）useful one. IS this your English d_?–Yes,it is very useful. this is ___to students of English A.a useful advice B.useful advice C.one of useful advices D.a pithis is ___to students of EnglishA.a useful advice B.useful adviceC.one of useful advices D.a piece of useful advice答案上说D,我想问问为什么