We hope that such a book ____is helpful to our research work is on sale.A.that B.as C.which D.till

题目

We hope that such a book ____is helpful to our research work is on sale.A.that B.as C.which D.till
我放进C,感觉还比较合适,却是错的,能不能帮我看看这题目,根据你的理解,解析和翻译下,
答案是选B,感觉很奇怪,估计不是such as 的结构~,就我个人觉得C应该比较合理,矛盾中,

答案

as引导一个定语从句修饰book而已阿 We主语 hope谓语 [that(such a book)宾语从句中的主语(as is helpful表语 to our research work)定语从句 is宾语从句中的系动词 (on sale)宾语从句中的表语]宾语从句