Contextual semantic functions of the nuclear sentence patterns in expending the communicative intention of the speaker and ways of their teaching

According to the purpose of the utterance: declarative, interrogative, imperative, exclamatory. The strictly declarative sentence immediately expresses a certain proposition, that is why the actual division of the declarative sentence presents itself in the most developed and complete form. The rheme of the declarative sentence makes up the center of some statement as such. The strictly imperative sentence does not express any statement or fact, i.e. any proposition proper. It is only based on a proposition, without formulating it directly. Namely, the proposition underlying the imperative sentence is reversely contrasted against the content of the expressed inducement. It is so because an urge to do something (i.e. affirmative inducement) is based on a supposition that something is not done. An urge not to do something (i.e. negative inducement) is founded on the supposition that something is done or may be done: Don’t talk about them (They talk about them).
The rheme of the imperative sentence expresses the informative nucleus not of an explicit proposition, but of an inducement – a wanted or unwanted action. The actual division of the strictly interrogative sentences is uniquely different from declarative and imperative sentences. It expresses an inquiry about information which the speaker does not possess. Therefore the rheme of the interrogative sentence, as the nucleus of the inquiry, is informationally open (gaping). Its function consists only in marking the rhematic position in the response sentence and programming the content of the rheme in accord with the nature of the inquiry. The thematic part of the answer is usually zeroed since it’s already expressed in the question: How are you? – Fine, thanks.⁵
The conception of the sentence is based on the alternative interpretation of the syntactic structure of the sentence, its functional or syntactic positions. Unlike the traditional grammar, which says that there are two principal parts in the sentence -the subject and the predicate, the verbocentric conception (or verb-centred conception) argues that the main part of the sentence is the verb. This conception has been worked out by L. Tesniere. According to this theory the verb determines the constituent structure of the whole sentence. L. Tesniere pictured the sentence as a "small drama", centred around an action, denoted by the verb-predicate and its participants which he termed "actants" (the subject and the object of the sentence) and "circonstants" (the time, the place, the quality of the action). In other words, the verb opens up some syntactic positions for other parts of the sentence. This combining power of the verb (or its comb inability) L. Tesniere called the valency of the verb. Thus, in the sentence "We started our journey at the dawn" the verb predicate "start" denotes an action, while the other parts denote its participants: "We" - the subject or the doer of the action, "journey" its object⁶.
Paradigmatics of the simple sentence is closely connected with the idea of the kernel sentence and sentence-derivation, which was introduced by N. Chomsky. He believed that all sentences generated in speech (that is surface structures) are derived from or can be reduced to some limited number of basic syntactic structures which he called "kernel". The sentence "He did the job carefully and thoroughly" can be reduced to the kernel sentence "He did the job". The sentence "I saw him come" is derived from two kernel sentences "I saw him" and "He came". The derivation of sentences out of kernel ones can be analyzed as a process falling into sets of transformational steps:
1. "morphological arrangement" of the sentence, i.e. morphological changes expressing syntactically relevant categories, such as the predicate categories of the verb: tense, aspect, voice, mood, e.g.: He writes. ~ He will be writing/would write/ has written;
2. "functional expansion" includes various uses of functional words, e.g.: He regretted the trip. ~ He seemed to regret the trip;
3. "substitution", e.g.: The children ran out of the house. ~ They ran out of the house. I want a different book, please. ~ I want a different one, please;
4. "deletion" - elimination of some elements of the sentence in various contextual conditions, e.g.: Would you like to go out? - To go out?
5. "positional arrangement", e.g.: A loud bang came from there. ~ From there came a loud bang;
6. "intonational arrangement", e.g.: They should do it on their own. ~ They? Should do it on their own?
Thus, the simple sentence is a monopredicative unit. The grammatical structure of a simple sentence is mainly determined by its syntactic pattern which presents a system of function-expressing positions, defined by the syntactic valency of the verb predicate.There's also one circonstant "at the dawn", which denotes the time of the action. Thus, the syntactic structure of the sentence according to L.Tesniere is conditioned by the syntactic valency of the verb predicate. The syntactic valency of the verb can be of two cardinal types: obligatory and optional. The obligatory valency is necessary realized in the sentence, otherwise the sentence is grammatically incomplete. Obligatory valency mostly refers to the actants - the subject and the object, (there are cases, however, when the adverbial can be also viewed as an obligatory position: e.g. The summer lasts into the early September. The optional valency is not significant for the competence of the sentence. It mayor may not be realized depending on the needs of communication.