Reduced adverbial clauses (also called participle clauses) replace full subordinate clauses with shorter participial phrases. They are a hallmark of formal and academic English, making sentences more concise and sophisticated.
Present participle (active meaning)
Replace active subordinate clauses with -ing participle phrases when subjects are the same.
Because she knew the answer → Knowing the answer, she raised her hand.
While he waited for the bus → Waiting for the bus, he read his notes.
Perfect participle (completed action)
Use having + past participle to show the first action was completed before the second.
After she had reviewed the data → Having reviewed the data, she submitted her report.
Because they had been informed → Having been informed of the changes, they adjusted their plans.
Absolute constructions
Use a noun/pronoun + participle when the participle clause has a different subject from the main clause.
Weather permitting, the event will take place outdoors.
All things considered, the project was a success.
Common mistakes
Not "Walking to work, the rain started." — say "Walking to work, I got caught in the rain.". Dangling participle: the subject of the participle (walking) must match the subject of the main clause.
Practise it
Check that the subject of the participle matches the subject of the main clause, unless you are using an absolute construction (Weather permitting, All things considered).