Most of the subordinating conjunctions and conjunctive pronouns and adverbs are polyfunctional as they introduce various kind of sub-clauses. (I remember the house where Iwas born). Normally the conjunctive adverb where introduces a spatial adverbial clause. Here where I was born is an attributive subordinate clause.
Most polyfunctional is the conjunction that which can introduce a great variety of sub-clauses : (an object clause) I know that he will never do that; (a subject clause) That this should be so cut her to the quick; (a predicative clause) What surprises me is that he never expected it; (a complement clause) It is the vastness of Russia that fascinates the traveler;(a clause of consequence) So great was her grief that shestood dumb, etc. We see that the conjunction does not determine the character of the clause.
Levels of Subordination
There are two basic types of subordination: parallel and consecutive. In parallel subordination sub-clauses refer to one and the same principal clause. (However hard he was working, whatever was happening, he never forgot me). Consecutive subordination presents a hierarchy of clausal levels. In this hierarchy one subordinate clause is commonly subordinated to another (I’ve no idea [1] why she said [2]she couldn’t call on us at the time [3]I had suggested).
Syntactic Processes in the Complex Sentence.
To the universally recognized processes within a complex sentence there refer contamination, parcellation andemancipation. In contamination two syntactic and semantic relations are fused, which results in contaminated (mixed) clauses {This man looked as if hewere suffering (J.Galsworthy). The clause underlined can be analyzed as a contamination of a predicative and an adverbial clause of unreal comparison. Parcellation consists in separating a sub-clause from the principal clause to rhematize (and emphasize) it (But princess Dragomiroff says that she married an Englishman. Whose name she cannot remember (A. Christie). Emancipation consists in a sub-clause turning into an independent sentence with a connective turning into an adverbial element (Supposing he comes? That he should have come to that! If only he were here today!).