－What did you do ________ your last day off?

    －I took my dog _______ a walk.

A. in; for              B. on; for          C. on; as           D. at; on

---What did you do ______ your last day off?
---I took my dog ______ a walk.

1. A.
   in; for
2. B.
   on; for
3. C.
   on; as
4. D.
   at; on