Professor Lee’s book will show you _________ in other fields．

1. A.
   how it can be used
2. B.
   when can it be used
3. C.
   where be used it
4. D.
   which can be used it

Professor Lee’s book will show you　　 in other fields.

A. how it can be used B. when can it be used

C. where be used it D. which can be used it