— What are you mailing, Tom?

— A textbook ______ a new method of teaching physics. I want my friend to take a look at it.

[      ]

A. is based on

B. based on

C. basing on

D. which based on

过渡时期总路线的主体是

A．对农业的社会主义改造

B．对手工业的社会主义改造

C．对资本主义工商业的社会主义改造

D．实现国家的社会主义工业化