It is believed that if a book is it will surely the reader.A. interested; interestB. int

问题补充：

It is believed that if a book is ，it will surely the reader.

A. interested; interest

B. interesting; be interested

C. interested; be interesting

D. interesting; interest

答案：

A. interested; interest

B. interesting; be interested

C. interested; be interesting

(答案→)D. interesting; interest

解析：考查现在分词作表语，表示主语的特征或性质。