--- ________ I remind you of is to return the book to our English teacher.  

    ---I will give it to him _________  I see him.   

A. That; immediately       B. What; directly       C. What; while       D. Whether; once

 --- ________ I remind you of is to return the book to our English teacher.  

    ---I will give it to him _________  I see him.    

   A. That; immediately  B. What; the moment 

C. What; while       D. Whether; once

---______ I remind you of is to return the book to our English teacher.  
---I will give it to him ______  I see him.

1. A.
   That; immediately
2. B.
   What; directly
3. C.
   What; while
4. D.
   Whether; once