Reduced Adverb Clauses : An Adverb Clause can be reduced only when the subject of the Adverb Clause and the subject of the Main Clause are the same :
1- Omit the Subject of the clause and the " BE " form of the verb :
While I was watching TV , I fell asleep.
While watching TV , I fell asleep.
2- If there is no " BE " , omit the subject and change the verb to " -ing " form :
After I signed the report , I gave it to the director.
After signing the report , I gave it to the director.
While the teacher was speaking, I fell asleep. ( cannot be reduced, because the subjects are different )
A : Reducing Adverbial Clauses of Time :
1 - Two actions happening at the same time :
Janet was sitting in an armchair and reading a book.
Janet was sitting in an armchair reading a book.
2 - One action happens during another action :
David was watching TV while she fell asleep.
David fell asleep watching TV.
3 - One action happens before another action :
After they found a hotel, they looked for a restaurant.
Having found a hotel , they looked for a restaurant.
B - Reducing Adverbial Clauses of Reason :
1 - The sentences answering " WHY " questions :
Since she felt sick, she went to bed early.
Feeling sick, she went to bed early.
2 - Negative :
I didn't know his address, so I couldn't contact him.
Not knowing his address, I couldn't contact him.
3 - Negative , ( one action happens before another action ) :
I had not understand what he said, so I asked him to repeat the directions.
Not having understood what he said , I asked him to repeat the directions.