1. An adverbial clause is a dependent clause that serves as adverbial modifier to the predicate or another member of the main clause:
Andrea couldn't type any more letters as her eyes were tired.
As Doris ran up the steps, she twisted her ankle.
Pretty as she was, nobody liked her.
2. Adverbial clauses can be joined syndetically, i. e. by means of subordinating conjunctions, or asyndetically (in which case a sentence could always be paraphrased so as to include a conjunction). An adverbial clause can precede, interrupt or follow the main clause. The general rule is to punctuate adverbial clauses placed in initial or medial position:
An Englishman, even if he is alone, forms an orderly queue of one.
3. According to their meaning we distinguish the following types of adverbial clauses: adverbial clauses of time, place, condition, reason, purpose, result, manner, comparison and concession.
Adverbial Clauses of Time
1. Adverbial clauses of time (or temporal clauses) are used to say when something happened by referring to another event:
I can't pay my bills until my paycheque comes.
Adverbial clauses of time are introduced by the following one-member and multi-member subordinators: when, before, by the time (that), the first/last/next time (that), wherever, since, directly, during the time (that), after, until, immediately, no sooner…than, as, till, once, hardly / scarcely / barely... when, as/ so long as, while, every / each time, the moment/minute, etc. (that).
2. As a rule, future tenses are not found in clauses of time; present tenses with a future reference are used instead.
3. Main clauses opening with the endorsing items barely, hardly, scarcely and no sooner have inverted word order. If these endorsing items occur in medial position, the word order is normal. These sentence models generally use the past perfect tense in the main clause and the simple past in the time clause.
If a clause of time preceding the main clause opens with only after, only when or not until, the main clause has inverted word order.
After wherever (and other -ever compounds in various types of subordinate clauses) we sometimes find the modal auxiliary may, which can imply a remote possibility.
Minor breakdowns, whenever they may occur, will be fixed promptly.
Adverbial Clauses of Place
1. Adverbial clauses of place are used to say where something happened by referring to the scene or direction of another event or process. Adverbial clauses of place are introduced by the subordinators where, wherever, anywhere, everywhere:
Where buildings were destroyed by the earthquake, rescue parties are now at work.
Sometimes an adverbial clause of place is preceded by a preposition:
I can see it clearly from where I'm sitting.
2. Present simple is normally used to denote a future action after the subordinators anywhere, everywhere and wherever.
Adverbial Clauses of Condition
1. Complex sentences with adverbial clauses of condition (called "conditional sentences" or "conditionals") are used to refer to an event, described by the main clause, that depends for its occurrence on another event (condition), described in the subordinate clause. Conditions may be thought of as real or unreal (hypothetical or counterfactual).
2. Adverbial clauses of condition are introduced by the following one-member and multi-member subordinators: if, so/as long as, on (the) condition (that), if…then, assuming (that), in the event that, unless, given that, suppose / supposing (that), what if, in case (that), provided/providing (that), say, once, on the understanding that.
3. An adverbial clause of condition can be joined asyndetically provided that it has inverted word order.
In asyndetic conditional sentences, the contracted forms Weren't, Shouldn't and Hadn't cannot be used to open a conditional clause; the corresponding full forms should be used.
4. In dealing with conditional sentences and their varied structure, two criteria should be taken into account: the time reference and presumed reality or unreality of the situation described. These factors combine to determine the choice of verb forms in conditional sentences. Accordingly, we distinguish three basic models of conditional sentences:
Type 1: situation thought of as real; present, past or future time reference.
Type 2: situation thought of as unreal or hypothetical; present or future time reference.
Type 3: situation thought of as unreal; past time reference.
Within these types there is considerable variation of form and meaning.
Adverbial Clauses of Reason
1. Adverbial clauses of reason (or cause) are used to give a reason for the event or situation named in the main clause or to say why the statement expressed in the main clause is true. Adverbial clauses of reason are introduced by the following one‑member and multi-member subordinators: because, now that seeing (that), as, in that considering (that), since, for the reason that, insofar as (formal), due / owing to the fact that, so / as long as, in view of the fact that, inasmuch as (formal), on the ground(s) that.
2. Adverbial clauses of reason introduced by as occasionally have inverted word order, with a predicative of the subordinate clause moved to the front. Cf.: Tired as she was, I didn't like to disturb her. As she was tired, I didn't like to disturb her.
Adverbial Clauses of Purpose
1. Adverbial clauses of purpose are used to indicate the purpose of an action. Purpose clauses are introduced by the following conjunctions: so that, in order that, lest (formal), that (old-fashioned), so (informal), in case, for fear (that), if (+ be to).
2. As purpose clauses refer to hypothetical or future events, they often employ a modal, a future verb or a subjunctive mood form. When the verb in the main clause is in the present or future, or else in the imperative mood, the purpose clause employs may, can or will. The present simple is also possible.
Besides, the purpose clause frequently employs the present simple if the predicate of the main clause includes a modal verb or a subjunctive mood form:
He should drive carefully so that he doesn't get fined.
When the verb in the main clause is in the past, the purpose clause employs might, could, should or would:
Before coming to class I put my name on the cover so that nobody would take my course book.
Adverbial Clauses of Result
1. Adverbial clauses of result describe the result entailed by an action or event named in the main clause. Result clauses are introduced by the following multi-member subordinators: (so)... that, (such)... that, so that, with the result that. Result clauses always follow the main clause:
We arrived ahead of time, so that we got the best seats.
2. Adverbial clauses of result introduced by so... (that) and such... (that) are also called adverbial clauses of degree.
The scope of his knowledge was such that he could lecture on any literary trend without using any notes. (or: Such was the scope of his knowledge that...)
3. Result clauses introduced with so that may look similar to clauses of purpose. However, their verb forms are different. A result is a "real" fact; therefore, the predicate of a result clause stands in the indicative mood (chiefly the simple present or past). A purpose is an "unreal" fact, or an intended result; therefore, the predicate of a purpose clause often includes a modal verb (usually should / would), or a verb in the future tense. Otherwise, the unreality is shown by the verb form in the main clause.
Adverbial Clauses of Manner
1. Adverbial clauses of manner are used to say how something is done by referring to another action, real or imaginary. Adverbial clauses of manner are introduced by the following one-member and multi-member subordinators: as, in a way, much as, (in) the way (that), as if, how (informal), as though, like (informal).
Notice the verb form variants in adverbial clauses of manner after as if and as though:
George writes as if he is left-handed. (One can infer from his handwriting that he is left-handed.)
George writes as if he was/were left-handed. (but he is not)
Adverbial clauses of manner joined by as can optionally have inverted word order, particularly when the subject is expressed by a long noun phrase.
2. The meaning of manner as expressed by adverbial clauses often implies comparison. However, clauses of manner differ structurally from clauses of comparison in that they do not correlate with an endorsing item in the main clause. Clauses of comparison, conversely, always require an endorsing item. Besides, clauses of manner can be used to elaborate the meaning of an adverbial modifier of manner, in which case they could be regarded as specifying adverbial clauses of manner.
Adverbial Clauses of Comparison
1. Adverbial clauses of comparison are used to compare two things or facts so as to say how they are similar or different. Adverbial clauses of comparison are introduced by the correlative subordinators as and than, with an endorsing item in the main clause. The endorsing item can be an adverb (as, more, less) or a morpheme (-er), modifying a comparative element.
2. Endorsing items in the main clause often combine with intensifying or limiting adverbs: half, much, far, etc.
The following structures are most often found in comparative clauses: as... as, not so... as, -er... than, more... than, not as... as, as... as if, less... than, nothing like, (much/nearly/almost/just about) the same... as.
A clause of comparison generally follows the main clause.
3. The present simple is often used to refer to the future in comparative clauses.
Adverbial Clauses of Concession
1. Complex sentences with adverbial clauses of concession express the admission that although something is true or accepted, another part of the problem, another view or situation (often unexpected) exists. Adverbial clauses of concession are introduced by the following one-member and multi-member subordinators: although, though, even though, even if,
while, whereas, granted that, whatever, wherever, whichever, whoever, not that, considering, whether... or, in spite of the fact that, despite the fact that, whenever, much as, however (good), no matter (what).
2. A concessive clause has inverted order if it opens with a predicative followed by the conjunctions as or though:
Handsome as/though he was, nobody liked him.
In this kind of structure as has a concessive meaning, as distinct from clauses of reason, where as retains its causal meaning whether the word order is inverted or not. Cf.: Tired as she was / As she was tired, I didn't like to disturb her. (an adverbial clause of reason)
Tired as she was, she went on typing. (an adverbial clause of concession).