1. Language means of expressing the theme and the rheme.

In comparison with the language means used to express the theme, language has a richer arsenal of means to express the rheme because the rheme marks the informative focus of the sentence. Many languages, like English, resort to different means in order to signal a new topic,

24. Classifications of Sentences

1. Classification of Sentences according to the Purpose of the Utterance

We find different classifications of sentences according to the purpose of the utterance.

Most grammarians follow the traditional classification and divide all sentences into declarative, interrogative, imperative and exclamatory.

2. Classification of Sentences according to Structure

The classification of sentences according to structure may be based on different grounds and therefore we can find very many different classifications.

According to the number of the principal parts several linguists suggest dividing sentences into two-member or double-nucleus and one-member and single-nucleus sentences.

A two-member sentence contains two principal parts – a subject and a predicate: The air was still. It may be either unextended comprising only a subject and a predi­cate as in the example given above or extended comprising besides the subject and the predicate some secondary parts: At the Captatint’s command the ship weighed anchor.

25. Simple and Composite sentences – a general overview

From the point of view of their structure sentences may also be divided into simple and composite sentences depending on whether the sentence contains only one subject-predicate unit or more than one such unit.

The term "composite sentence" seems to have been intro­duced by H. Poutsma as a common term for both the compound and the complex sentence and has been accept­ed by those scholars who adhere to the traditional trichotomy. The trichotomic classification of sentences into simple, compound and complex was established in the middle of the nineteenth century and has remained the prevalent scheme of the structural classification of sen­tences.

A simple sentence contains only one subject-predicate unit: "Helen sighed. They talked about many things." A composite sentence contains more than one subject-predi­cate unit: "She's a very faithful creature and I trust her. If I let this chance slip, I am a fool." In a compos­ite sentence each subject-predicate unit with the words attached to it is called a clause, a concept established in the nineteenth century. There are two kinds of compos­ite sentences: compound and complex sentences.

Compound sentences have been defined as those containing syntactically independent co-ordinated clauses.

Complex sentences are those which include both independ­ent and dependent clauses. The semantic relations, which can be expressed by sub­ordination are much more numerous and more varied than with co-ordination and so are the means expressing sub­ordination. The means expressing subordination are different conjunctions and conjunctive words.