These clauses refer to the TIME that the main clause occurred. They are usually introduced by subordinating conjunctions that refer to time.
Some examples are:
AFTER she waxed her legs, she clipped her toenails.
I had never seen such a big one BEFORE I met you.
SINCE the caretaker left, we haven’t been able to tend the yard.
Ecstasy wasn’t available UNTIL the drug MDMH was discovered.
WHEN man gets to Mars, we will be old and gray.
AS SOON AS we get there, I’ll change the baby’s diaper.
I haven’t been to a roaring party SINCE my high school reunion.
WHILE her attention was momentarily adverted, I swiped some gum.
SOONER THAN you realize, you’ll be as tall as me.
*NO SOONER had the firms merged, (WHEN) I was fired.
*NB: This “complex subordinating conjunction”, when used in the initial position, requires the use of an “inversion”.
e.g. NO SOONER WILL YOU GET THE PROMOTION AND THE COMPANY WILL GO BELLY UP.
In inversions, the AUXILIARY VERB (will, in this case) is placed before the subject (you), as in question format. In the standard order, the sentence would be:
e.g. YOU WILL NO SOONER GET THE PROMOTION AND THE COMPANY WILL GO BELLY UP.
When can be misleading due to the fact that it sometimes works as a subordinating conjunction for noun clauses.
e.g. THE LADY AT THE CHECK-IN KNOWS WHEN THE PLANE IS SCHEDULED TO LAND.
- “when the plane is scheduled to land” is the direct object of the transitive verb “know”. Therefore, it is not an adverbial clause of time, but rather a finite noun clause working as a direct object.
And it (the word WHEN) can be a relative pronoun when it describes a noun that refers to time.
e.g. THE TOOK A RISK AT A TIME WHEN ALL HOPE WAS LOST.
- “when all hope was lost” is the finite restrictive adjective clause describing the noun phrase “a time”
- “at a time” is a prepositional phrase working as an adverbial phrase of time.
NON-FINITE ADVERBIAL CLAUSES OF TIME
It is common to reduce these clauses with the GERUND and the PAST PARTICIPLE.
e.g. WHEN CHOOSING YOUR WORDS, YOU SHOULD CONSIDER HER EMOTIONAL STATE.
- “When choosing your words” is the adverbial clause of time modifying the main clause “you should consider her emotional state.”
- “When choosing your words” has been reduced by the gerund. In a finite format, it would be “When you choose your words.”
- “When choosing your words”, therefore, is a non-finite adverbial clause of time reduced by the gerund.
- “When” is a subordinating conjunction that can be used together with the reduced form. Not all subordinating conjunctions are as flexible.
e.g. HAVING UNDERSTOOD THE METHOD, HE WENT ON TO FINE TUNE ALL THE DETAILS.
- “Having understood the method” has been reduced by the gerund. In a finite format it would be “When he had understood the method.”
- “Having understood the method”, therefore, is a non-finite adverbial clause of time reduced by the gerund.
- As you can see, it is possible to reduce perfect tenses using the gerund.
e.g. PLACED UNDER A MORE FLUORESCENT LIGHT, THE COLOR BECOMES MORE VIBRANT.
- “Placed under a more fluorescent light” has been reduced by the past participle. In a finite format, it would be “When the color is placed under a more fluorescent light.”
- “Placed under a more fluorescent light”, therefore, is a non-finite adverbial clause of time reduced by the past participle.
UNTIL x BY
These two ADVERBS OF TIME can be very confusing. UNTIL gives the idea of CONTINUITY. BY gives the idea that something will happen anytime “before, but no later than, the time reference”.
e.g. THE LAW REMAINS IN FORCE FOR ALL ELECTIONS UNTIL 15TH FEBRUARY THE FOLLOWING YEAR.
- “until 15th February the following year” shows that the law will CONTINUE in force TO THAT POINT IN TIME.
e.g. SHARKS WILL BE EXTINCT IN THE WILD BY THE YEAR 2007.
- “by the year 2007” gives an idea that “sometime before 2007 sharks will be extinct.” It is NOT CLEAR WHEN, but it is expected to happen “sometime” before the time reference.