This is that they all want to but it.A. a so useful bookB. such an useful bookC. a such us

问题补充：

This is that they all want to but it.

A. a so useful book

B. such an useful book

C. a such useful book

D. so useful a book

答案：

A. a so useful book

B. such an useful book

C. a such useful book

(答案→)D. so useful a book

解析：such a/an +形容词+名词=so +形容词+a/an +名词。