What is a reduced adverb time clause?
An adverb clause of time (after I finished work, before I played it) can often be shortened. We cut the subject and the tense, and leave a time expression + an -ing form. The meaning stays the same; the sentence just becomes tighter and slightly more formal.
| Full clause | Reduced clause |
|---|
| After I have been studying all day, I like to relax. | After studying all day, I like to relax. |
| Before I played it, I never thought I'd enjoy it. | Before playing it, I never thought I'd enjoy it. |
| Since I learned to ride, I haven't played a single game. | Since learning to ride, I haven't played a single game. |
How the clause is reduced depends on the time expression you start with. There are two routes.
Route 1 — before, since, after
Keep the time expression, delete the subject, and change the verb to the gerund.
before / since / after + -ing form + … , + main clause
After finishing her degree, she moved to Berlin.
Before signing anything, read the small print carefully.
Since moving to the coast, I haven't had a single cold.
The reduced clause can also come second: I always check the weather before going out.
Or use a noun. If a noun exists for the action, it often sounds even better:
After the meeting, nobody said a word. · Since her arrival, everything has changed.
Route 2 — as soon as becomes on
As soon as does not survive the reduction. Delete it, replace it with on, remove the subject, and change the verb to the gerund.
on + -ing form + … , + main clause
As soon as she heard the news, she phoned her mother. → On hearing the news, she phoned her mother.
As soon as we arrived, we went straight to bed. → On arriving, we went straight to bed.
Note: on + -ing means immediately after. It belongs to formal and written English — news reports, narrative, academic writing. Upon is the same thing, one degree more formal still.
The golden rule: one subject
You can only reduce a time clause when both clauses share the same subject. The reduced clause has no subject of its own, so the reader assumes it belongs to the main clause.
✓ I locked the door before I left. → I locked the door before leaving.
✗ Before I left the house, the phone rang. → Before leaving the house, the phone rang. (the phone did not leave the house)
Tip: while and when reduce the same way — While waiting for the bus, I read three chapters. The same-subject rule still applies.
Common mistakes
Almost every error here is one of four things: keeping the subject, keeping as soon as, using an infinitive, or reducing when the subjects differ.
⚠ Common mistakes:
✗ After I studying all day… → ✓ After studying all day…
✗ …before to play it. → ✓ …before playing it.
✗ As soon as arriving home… → ✓ On arriving home…
✗ On hear the news… → ✓ On hearing the news…
✗ Since move to the coast… → ✓ Since moving to the coast…