A. Use an -ing form when the original verb is intransitive.
- Walking along the street, Tom ran into one of his old friends.

B. Use an -ing form when the original verb is transitive and when its object comes after it.
- Facing a police officer, he chose to run away.

C. Use an -ed form when the object of its original verb serves as the subject of the main clause.
- Located on a hill, the hotel commands a fine view.