—What were you doing when the UFO arrived?— I         with my dog on the street.

A. walked           B. was walking      C. is walking       D. have walked

---What were you doing when the UFO ______?

   ---I ______ a milk shake.

   A. reached, made   B. reached, was making   C. arrived, made   D. arrived, was making

—What were you doing when the UFO arrived?

— I         with my dog on the street.

1. A.
   walked
2. B.
   was walking
3. C.
   is walking
4. D.
   have walked