Answers to tasks: What are the main functions of language?

How is the language system organized (structured)? What does the hierarchy of levels imply?
In modern linguistics language is regarded as a system of signs which is organized by the principle of hierarchy of levels of lingual units. The peculiarity of this hierarchy lies in the fact that units of any higher level are formed of units of the immediately lower ones.
Describe each level of the hierarchical structure of language system (phonemic, morpho-logical, lexemic, syntactic and textual levels).
The lowest level of lingual units is a phonemic level which is formed by phonemes.they differentiate morphemes and words from each other. For instance: bad [bæd] and bed [bed];The level located above the phonemic is a morphemic or morphological level. The morpheme is the smallest meaningful component of the word.The third level in the lingual hierarchy is the lexemic level represented by words as lexical items or lexemes.The fourth level in the hierarchy of language system is the syntactic level the main unit of which is a sentence. The highest level of lingual units is the textual level represented by a text.
Give the structural definition of the text and explain it.
text can be defined as a sequence of thematically interrelated sentences which forms a meaningful whole. According to the structural definition, the lower border of the text is restricted as it implies a sequence of at least two sentences. However, the structuralist approach to text definition leaves its upper border open because of the varying diapazon of the theme.
Name structural types of texts and define them.
In microtexts sentences centre around one concrete theme while in macrotexts - microtexts are united by a hypertheme which is derived from the constituent microthemes.
Give the functional definition of the text.
lingual unit of any length, be it a sequence of thematically interrelated well-formed sentences, one simple sentence or even a word, can be defined as a text if it performs a communicative function. This definition explains the existence of such small-scale texts as: "Fire!"; "Help!" and many others
In the development of English grammar two basic periods are distinguished: 1. prescientific period ( from the end of the XVI ^th century till the beginning of the XX th century) with prenormative (descriptive) grammar and normative (prescriptive, demanding) grammar; 2. scientific period ( from the turn-of-the century up to the middle of the 20^th century) with scientific explanatory grammar.