Answer: Add a subject
Explanation:
With regards to the group of words given "Went for a walk and saw the old candy shop", to make the sentence complete, a subject needs to be added.
By adding the subject will make the sentence complete. For example, adding a subject such as Henry will make the sentence "Henry went for a walk and saw the old candy shop". This then makes the sentence complete.
I know a lot of other languages (including Korean) but I have never heard of that. I asked my language teacher, and even she didn't know, so I don't know if that is even something.