|The Structure of English Language - Clause Functions|
The simplest sentences may contain a single clause. (Simple is a standard description of one kind of sentence.) Where a sentence contains more than one clause, these may be considered of equal grammatical importance. If this is so, these are coordinate clauses. They are joined by a coordinating conjunction, such as and or but. (Some grammarians call the first clause of the sentence the main clause, and the others coordinate clauses). Here are some examples. Apart from the conjunctions (or, so and and, everything else is a main/coordinate clause):
Sometimes the clauses are placed in a hierarchy: the more important ones are main clauses, while the less important are subordinate clauses. A main or coordinate clause could stand on its own as a sentence, but a subordinate clause works only within a sentence. A subordinate clause can do the job of other clause elements. It can work as subject, object, complement and adverbial, as in these examples:
Clauses that function as subject, object or complement replace noun phrases, so they are called nominal clauses. Those that function as adverbs/adjectives are adverbial/adjectival clauses.
Some other kinds of nominal clauses are shown below. For clarity, they are all shown in object position. This is not the only place where they may occur, but is the most common.
These are introduced by a subordinating conjunction, which explains the adverbial meaning of the clause. These include when/before/after/while (time); because/since (reason); if/unless/lest (condition), as in these examples:
Two minor types of adverbial clause are inf. and -ing clauses.
A familiar type is the relative clause, introduced by a relative pronoun (who, whom, whose, that, which), as in these examples:
The relative pronouns are in brackets, as they may be omitted if understood.
Two minor types of adjectival clause are -ing and -ed clauses.
Since past participles do not all end in -ed we may find other verb forms in such clauses: The tea drunk by the students or the exam taken by the pupils.
Clause elements may be single words of the appropriate category, they may be phrases or even some kinds of subordinate clause. Explaining even simple structures is difficult. Verbal explanations are less easy to make than diagrams. These work best when there is a hierarchical level, as sentences are analysed into clauses, which are further analysed into (more clauses and) phrases, which are analysed into words, which are analysed into morphemes.
In an exam, you are very unlikely to be required to analyse long sequences. Use clause analysis (or phrase analysis) selectively, to establish some point about language acquisition (learning to make or understand structures), about language and society (how structures embody social attitudes to language), language change (how structures or paradigms change over time) or stylistics (how structures embody style).