—What are you mailing, Tom?
— A textbook a new method of teaching physics. I want my friends to take a look at it.
A. is based on
B. based on
C. basing upon
D. which based upon
网友回答
A. is based on
(答案→)B. based on
C. basing upon
D. which based upon
解析：句意：上文，你在邮寄什么？下文，一本以新的物理教学方法为基础的教科书，我想让我的朋友看一下。动词短语base on与其逻辑主语A textbook是被动关系，故用过去分词作定语，选B。