Have you read the book is about the moon?A. whatB. it C. / D. which

问题补充：

Have you read the book is about the moon?

A. what

B. it

C. /

D. which

答案：

A. what

B. it

C. /

(答案→)D. which

解析：考查定语从句引导词。前置语为the book名词，用which代替。it 和what不能作定语从句的引导词。