Here are the completed sentences using relative clauses:

7. Where is the nearest shop **that sells groceries**?
8. The man **who is wearing a red hat** is my father.
9. We encountered Jonathan and his cat **that he rescued**.
10. I want to know the reason **why you did that**.
11. The book is about the girl **who won the contest**.
12. They enter the building **that was recently renovated**.
13. The shop assistant has forgotten the customer **who was waiting**.
14. They visited the country **where they were born**.
15. Jessica was working on a computer **that was very old**.
16. I can't find anything **that fits**.
17. A compass is a tool **that helps you find direction**.
18. I don't remember the day **when we first met**.
19. Everybody loves Owen, **who is very kind**.
20. This is the most exciting game **that I've ever played**.