The Complex Sentence is a polypredicative construction built up on the principle of subordination. The Complex Sentence of minimal composition includes two clauses - a principal one and a subordinate one. Although the principal clause positionally dominates the subordinate clause, the two form a semantico-syntactic unity, in which they are interconnected.
The subordinate clause is joined to the principal one either by a subordinating connector (subordinator) or asyndetically.
A complex sentence does not always consist of one main and one subordinate clause. It may contain two, three, or more subordinate clauses, which may or may not be connected with one another. Two subordinate clauses are connected with one another if they belong to the same type. In this case they may be joined by a co-ordinating conjunctions (and, but, or).
Another type of structure is seen when the subordinate clauses are not connected with each other. For instance, one of two attributive clauses within a complex sentence may modify one part of the head clause, and the other attributive clause may modify another part: e.g. On the contrary, here I have everything that disappointed me without anything that I have not already tried and found wanting.
In a similar way two adverbial clauses within a complex sentence may belong to different homogeneous predicates in the head clause, etc.
It is obvious that many varieties are here possible.
The subordinate clauses contained in one complex sentence may have different functions: one may be attributive, another an object clause, a third may be adverbial, and so on.
Subordinate clauses of the first degree are clauses subordinated to the main clause.
A subordinate clause may also have another clause subordinated to it, that is, a subordinate clause of the second degree. The clause of the first degree to which another clause (of the second degree) is subordinated, has a twofold () syntactical connection: on the one hand, it is a subordinate clause with reference to the main clause, and on the other, it is a head clause with reference to the second-degree subordinate clause.
There may also be homogeneous clauses, that is, two or more subordinate clauses, connected either with or without a conjunction, and performing the same syntactical function in the sentence. These clauses may or may not be introduced by the same subordinating conjunction or connective.
The conjunctions which connect clauses may be divided into co-ordinating and subordinating and clauses may be co-ordinated and subordinated.
There are three criteria distinguishing conjunctions and clauses of different types:
(1) the function of the clause as compared to the corresponding element in a simple sentence,
(2) the lexical meaning of the conjunction itself,
(3) the possibility or impossibility of the clause in question being used outside the syntactical context in which it is usually found.
The question arises whether we call a conjunction subordinating because it introduces subordinate clauses or do we call a clause subordinate because it is introduced by a subordinating conjunction.
The principles of classification:
Subject-objectattributive-adverbial-functional
1) The subject clause expresses the theme of the actual division of a complex sentence: e.g. What he would do next was not even spoken of.
2) The object clause denotes an object-situation of the process: e.g. She cannot imagine what you are doing there.
3) Attributive clauses express some characteristics: e.g. I shook out my scarf which was damp.
4) Clauses of adverbial positions constitute a vast domain of syntax which falls into many subdivisions.
5) The predicative clause performs the function of the nominal part of the nominal part of the predicate, i.e. the part adjoining the link-verb: e.g. Work is what keeps life going. My only terror was lest my father should follow me. Lignose looked as though a sculptor had moulded it.
