--- Mr. Green, I think physics is too difficult for me.

---Tom, work hard, _______ you’ll find it not as difficult.

 A. or                  B. but              C. so               D. and

--- Mr. Green, I think physics is too difficult for me. 

---Tom, work hard, _______ you’ll find it not as difficult.

1. A.
   or
2. B.
   but
3. C.
   so
4. D.
   and

--- Mr. Green, I think physics is too difficult for me.
---Tom, work hard, _______ you’ll find it not as difficult.