§ 166. An adverbial clause of time characterizes the action expressed in the main clause from the temporal point of view. The action may be expressed by a finite or non-finite form of the verb.
An adverbial clause of time may be introduced by conjunctions: as, as soon as, as long as, when, whenever, while, now that, till, until, after, before, since; recently formed conjunctions and phrasal conjunctions: the time (that), the day (that), the moment, the instant, next time, every (each) time, directly, immediately, instantly, once.
Every conjunction in the above list imparts a particular shade of meaning to the temporal relation – priority, simultaneity, succession of actions, the beginning or the end of the action, repetition, coincidence of two actions, gradual development of a process, etc. These temporal relations can be illustrated by the following examples:
When a Forsyte was engaged, married, or born, the Forsytes were present. Whenever there was a pause, he gently asked again. (The conjunctions when and whenever introduce clauses expressing repetition.)
As they stood up Ivory clapped him on the shoulder. (The subordinate clause denotes the moment when the action of the principal clause takes place.)
While he walked around Christine sat and knitted at a distance. (The predicate in the subordinate clause expresses a durative action, which coincides in time with the action expressed by the predicate in the main clause.)
And now that Cecily had married, she might be having children too. Our hostess, once everyone had arrived, was full of good humor. (In both these cases the predicate in the subordinate clause expresses a prior action which fixes the moment from which the action or state expressed in the main clause becomes possible; therefore the subordinate clause of time has a shade of causal meaning.)
As they approached the house, they became quieter and quieter. (Both the actions are gradually developing.)
They were calling each other ‘George’ and ‘Elizabeth’ before they reached Camden Town. (The subordinate clause points to the moment before which the action of the main clause was in progress. The action of the predicate in the subordinate clause is posterior.)
The heavy guns began again soon after it was light. (The action of the subordinate clause, which is prior, fixes the beginning of the action in the main clause.)
The conjunctions till and until introduce clauses which fix the end of the action in the main clause if the latter contains no negation, as in:
She resolved to wait till Clym came to look for her.
If the time reference in the subordinate clause with till or until is to a commencement point, the main clause is always negative. For example:
He did not say a word till he was asked.
They did not marry until she was forty.
The boy did not start to read until he went to school.
Corresponding sentences with affirmative main clauses are impossible unless, the conjunction before is used.
*He said a word till he was asked ——> He said some words before he was asked.
*They married until she was forty ——> They married before she was forty.
The conjunction since may introduce a clause which indicates the beginning of a period of time continuing until now or until some time in the past. In the first case the present perfect is used in the principal clause, in the second the past perfect. In a temporal clause the past indefinite tense is used in both cases. For example:
I have only seen him once since I left school.
She had been such of a companion to him since she was three years old.
If the actions are expressed in both clauses are durative and still continuing, the present perfect tense is used in both the clauses, as in:
Since we have been friends we have never quarrelled.
Conjunctions of recent formation have mainly been formed from nouns denoting time, although some are formed from adverbs denoting time. They are the time, the moment, the instant, immediately, directly and others. Most of them are used to introduce subordinate clauses denoting the exact moment of the action in the main clause or the quick succession of the actions in both clauses.
We’ll be married the very moment we find a house.
Immediately he had lain down and closed his eyes, his consciousness went racing on without him.
Directly he saw me, he slipped back into the room.
Some of the temporal conjunctions are not confined to clauses of time. Thus as may be used to join clauses of cause, manner, concession, comparison and also to introduce parenthetic clauses. The conjunction since may introduce clauses of reason. The conjunctions when and while may express adversative relations, in which case they can hardly be considered subordinating conjunctions. When can introduce a clause containing a new piece of information, not prepared for by the preceding narrative, and thus indicates a quick succession of actions. The conjunction whenever generally expresses temporal relations, but the idea of time often mingles with that of concession.
At the sound of that knock she jumped up, when the brass candlestick clattered to the floor. (The
conjunction when expresses the quick succession of actions.)
She left the room in the pursuit of her duties, when no duty could have taken her away if she had wished
His life has been ruined for him, when he is but one-and-twenty. (In the last two sentences the conjunction
when expresses a concessive relation.)