In these cases, "when" and "where" introduce clauses that describe a noun the refers to a time or place, making them work as relative pronouns in these sentences. 1. This is the boy --had an accident.
2. Yesterday I saw a car was really old.
3. Mandy is the girl I met on Friday.
4. I haven't seen Frank, brother is five, for a long time now.
5. The robber stole the car the lady parked in front of the supermarket.
6. This is the man house is on fire.
7. Can I talk to the girlis sitting on the bench?
8. The book you gave me is great.
9. She likes hamburgers are hot.
10. Bill Clinton,-- was President of the USA,