It has been noted in grammar books that there exist more than three hundred definitions of the sentence but it seems hardly possible to arrive to a complete and exaustive definition of the sentence because the unit itself possesses so many specific features that any attempt to define it in all respects would seem futile. Moreover, the philosophical outlook and the linguistic conception of scholars predetermine their approach to the main communicative units of language.
a) The sentence is identified as a syntactical level unit possessing the distinguishing features of such level-units and occupying its appropriate place in the hierarchy of syntactic units.
b) The sentence is a predicative unit of quite definite type which is a lingual representation of predicative thoughts.
c) The sentence is the main syntactic unit and the highest linguistic form which may occur as part of the supersyntactic structural forms. The sentence itself Is not a mere composition of words and word-groups, it is a constructive integration of all the lower language units.
d) The sentence is a very complex linguistic entity. Its complexity is revealed both in its content and expression sides. The content of the sentence is the complex of semantic features whereas the expression of the sentence is represented by the complex of its formal characteristics.
e) the sentence is undoubtedly the main communicative unit of human language with the help of which speech communication is achieved, and without which the latter is inconsistent. The communicative force of the sentence is its distinguishing qualitative characteristics which makes it dominant over the rest of syntactic units of non-predicative and of predicative nature.
The composite sentence, as different from the simple sentence, is formed by two or more predicative lines.
Each predicative unit in a composite sentence makes up a clause in it, so that a clause as part of a composite sentence corresponds to a separate sentence as part of a contextual sequence. E.g.:
When I sat down is dinner I looked for an opportunity to slip in casually the information that I had by accident run across the Driffields; but news travelled fast in Blackstable (S. Maugham).
The cited composite sentence includes four clauses which are related to one another on different semantic grounds. The sentences underlying the clauses are the following:
I sat down to dinner. I looked for an opportunity to slip in casually the information. I had by accident run across the Driffields. News travelled fast in Blackstable.
In combination of sentences into larger units we may observe two different types of grammatical relationship based upon relative position and interaction of sentences. These are co-ordination and subordination. This classification remains the prevalent scheme of the structural classification of sentences in the grammars of all types in various languages. A very important syntactic concept developed along with this classification is the concept of syndeton and asyndeton.
Sentences joined together by means of special function words designed for this purpose are syndetic those joined without function words are asyndetic (or contact-clauses).
Compound sentences are structures of co-ordination with two or more immediate constituents which are syntactically equivalent, i. e. none of them is below the other in rank.
Complex sentences are structures of subordination with two or more immediate constituents which are not syntactically equivalent. In the simplest case, that of binary structure, one of them is the principal clause to which the other is joined as a subordinate. The latter stands in the relation of adjunct to the principal clause and is beneath the principal clause in rank. The dependent clause may be either coordinate or subordinate.
The constituents of a composite sentence are organically interrelated and as such are not independent elements of a single syntactic unit 1.
Our starting point in describing the multiplicity of ways in which English sentences may logically be combined in actual usage will be to distinguish one-member and two-member composite sentences.
This distinction is a reality in both, speech and writing, but it often has no formal markings other than intonation in the one case and punctuation in the other.
The linguistic essence of these two types of composite syntactic units is best understood when viewed in terms of their meaning and structural peculiarities.
As we shall further see, a major point of linguistic interest is presented also by the correlation of the verb-forms in the component parts of a composite sentence and its functioning in different contexts of communication.
It is noteworthy that when two sentences occur together as constituents of an utterance, their relationship is indicated by at least one and sometimes ail of the following features: