Is that a book in farming? I want to borrow it.A. So it isB. If soC. So is itD. So if

问题补充：

Is that a book in farming? ,I want to borrow it.

A. So it is

B. If so

C. So is it

D. So if

答案：

A. So it is

(答案→)B. If so

C. So is it

D. So if

解析：考查省略句：根据上下文：if so=if it is a book in farming，句意是：这本书是关于农业的吗？如果是，我想借。选B。