  A present participle clause can express: An action happening at the same time as the action in the main clause: Tom lost his keys (while) walking through the park. (Tom lost his keys while he was walking through the park.) She left the room singing happily. (She left the room as she was singing happily.) The participle clause can come first in literary styles: (While) walking through the park, Tom lost his keys. Present participle clauses

  An action happening just before another action: Opening the envelope, I found two concert tickets. (I opened the envelope and I found two concert tickets.)

  An action that is the result of another action: Moments later a bomb exploded, leaving three people dead and twelve other injured. When I entered they all looked at me, making me feel uncomfortable.

  A reason for the action in the main clause: Having nothing left to do, Julie went home. (Since Julie had nothing left to, she went home.) Knowing a little French, I had no difficulty making myself understood. (As I knew a little French, I had no difficulty making myself understood.) Working as a sales rep, I get to travel a lot. (I travel a lot because I work as a sales rep.) Here the subjects of the two actions can be different: The weather being nice, we decided to go for a picnic. (As the weather was nice, we decided to go for a picnic.)

  Past participle clauses replace passive voice finite clauses: Shocked by the explosion, the people ran for shelter. (The people were shocked by the explosion and ran for shelter.) The musicians stood up, surrounded by thunderous applause. (The musicians stood up while they were surrounded by thunderous applause.) Past participle clauses

  If we want to emphasise that an action happens before another one, we use a passive perfect participle: Having been nominated three times for an Oscar, he is one of today's most acclaimed film directors.