Today it is a challenge to get a proper solution in terms of linguistics. Significant contribution to the development of this problem has made A. A. Shakhmatov

CHAPTER 2 FEATRURES OF SIMPLE AND COMPLEX SENTENCES
2.1  Features of simple sentences
To date, a large number of opinions and definitions of the sentences have been formed. For example, D. E. Rosenthal defined the sentence as the "minimal unit of human speech ", which is a grammatical compound of words (or one word), which have a certain semantic and intonational completeness. As a unit of communication, the sentence together is the unit of formation and expression of thought. In his opinion, the sentence is correlative with the logical proposition, however, it is not identical to it: the sentence can express a question, motivation, exclamation, assertion. Reflecting the activity of the intellect, it serves to express emotions and wills entering into the spheres of feeling and will"[40, 293]
AA Shakhmatov, a famous Russian linguist, believed that a sentence is the basic unit of syntax, since a sentence is formed in the sentence that the speaker or writer wants to express. Thus, he characterized the sentence on the grounds: the sentence has a grammatical basis and it is a statement about the subject of speech: communication, motivation, the question is a variety of utterance, the sentence is the unit of communication, and it is characterized by intonation completeness.
Highlighting these signs, A.A. Shakhmatov also determined the structure of the sentences - the form of the structure is determined by the grammatical basis. It can consist of two main members (subject and predicate) or one main member. He also divided the sentences into simple and complex (by the number of grammatical bases).
Building a simple English sentence is the most important for understanding the entire structure of the English language. It is so important because it applies to almost every English sentence, i.e. no English sentences can be properly constructed without knowing the material of this topic. If this topic is clear, then with the study of English there will be no problems - and vice versa.
So, the construction of sentences in any language is a correct description of real life situations. To correctly describe a situation, you need to take the words (names of objects and concepts) involved in this situation and combine them so that from these words you can get a picture of how objects interact with each other. We connect the words correctly, so in the head of the interlocutor there will be exactly the same picture that was conceived by us. We will connect words incorrectly and the picture will be distorted. Then the interlocutor will have to correct it himself, i.e. make extra efforts to correctly understand the situation described by us. Sometimes this is possible (if mistakes made during the combination of words were insignificant), sometimes - no (for very gross errors). 
For example:
Yesterday my relatives came from Tashkent (correct).
Yesterday my relatives go from Tashkent (wrong, but understandable)
Yesterday my relatives go Tashkent (it is wrong, difficult to understand the situation).
From the examples given, one can see how important ways in a language are the ways of combining words in sentences. From the examples given, one can see how important ways in a language are the ways of combining words in sentences.
E five ways in different languages are different, so trying to construct sentences in a foreign language is similar to the native language is most often futile - we cannot move the picture (the situation) from his head in his interlocutor's head.
We already know that in Russian the main work on the combination of words in the sentence is performed by the endings. Therefore, foreigners studying the Russian language are forced to memorize a huge number of Russian graduations. In English, there are no endings at all. They are not needed, since all the work on connecting words in a sentence is performed by a predicate. The predicate is what we should study in English first of all, if we want to correctly and intelligently express our thoughts in this language. But there is a predicate in the Russian sentence too. Yes, there is, although in its importance it is much inferior to the English predicate, because a huge portion of the work is done by graduation. It turns out that in Russian the predicate works as if paired with endings, and in English - independently, although the amount of work performed is the same. Hence, the English predicate contains something that compensates for the lack of endings, which is not the case with the Russian predicate.
This "something" - the nature of the action! Remember this concept. When compiling Russian sentences, we do not need it at all. When constructing any English sentence, we must necessarily determine the nature of the action of the predicate. Without this, it is impossible to build correctly any English phrase.
Depending on the purpose of the utterance, the sentences are narrative, interrogative and exclamatory. Shanskiy explains this in detail:
"A sentence is always addressed to someone: the speaker (the writer) refers to the listener (the reader). The purpose of the appeal may be a message of information, a request for information, or a volitional influence on the interlocutor. In the first case it will be used narrative proposition voltage, the second - the interrogative, the third - motive"[48, 539-540]
Narratives are called sentences, which contain a message about some fact of reality, phenomenon, and an event. Contain a message or description, and expresses a relatively complete thought, which is based on judgment. Completeness of thought is expressed in intonation: narrative sentences are characterized by a drop in tone at the end of the sentence.
Narrative sentences are the most common type of sentences, they are very diverse in content and structure, differ in the relative completeness of the thought, transmitted by a specific narrative intonation: an increase in tone on a logically allocated word (or two or more, but one of the increases will be the largest) and calm lowering the tone at the end of the sentence: The tug pulled up to the porch of the commandant's house. The people recognized Pugachev and fled after him in a crowd (AS Pushkin). The essence of narrative sentences in the Russian language is that, in a communicative sense, they communicate a complete thought about the phenomena of reality, fact and event.
Intonationally, narrative sentences are pronounced at an average pace: the tone of speech slowly rises, and towards the end of the sentence it gradually decreases. Narrative sentences may be unreported and common; in composition - two-part and one-part.
A narrative sentence can be:
Description: The rider sat in the saddle deftly and carelessly
(M. Gorky); Narration about actions, events: The old man walked calmly and cheerfully from stone to stone and soon disappeared among them (M. Gorky);
Message about the desire or intention to commit an action: I would not have played so much (A. Tvardovskiy);
By classifying narrative sentences, P.A. Lecant sentences various ways of expressing intonation. As mentioned above, for such sentences it is characteristic to lower the tone at the end. "A decline is especially noticeable when in the middle of a sentence on a word the voice rises significantly. A noticeable drop in tone is not observed in single-sentence sentences, for example in impersonal or nominative sentences, but in this case the voice should not be raised. In the widespread nominative sentences, the voice gradually decreases from the beginning of the sentence to the end"[30, 388]
There are also interrogative sentences. Questioning is called sentences aimed at inducing the interlocutor to express an idea of ​​interest to the speaker, that is, their goal is cognitive. Interrogative sentences involve the question of something unknown to the speaker. Means of expressing interrogation are: a special interrogative intonation, interrogative words (pronouns and adverbs), interrogative particles (is it really, perhaps,) and the order of words.
Interrogative sentences usually contain a question aimed at inducing the interlocutor to express an idea of ​​interest to the speaker. It serves to express the question. With the help of it, the speaker wants to get new information about something, confirm or deny any assumption. The interrogative sentence has its own grammatical form, which is represented by intonation, interrogative words, particles, and on the letter is indicated by a question mark.
For interrogative intonation, there is a more or less significant increase in tone at the end of the sentence, which is especially noticeable when compared with narrative sentences. An essential feature of interrogative intonation is an increase in the tone of the word, in which the essence of the question is laid, the singling out of this word (cf.: Will the father come by this train?) - Will the father come by this train?)[16, 206-214]
The main types of sentences. Depending on the content of the subject, you can classify the sentences in a well-known manner and identify certain general types of sentences.
The main line here is between personal sentences and impersonal sentences.
A personal sentence is a sentence in which the subject indicates a subject that is more or less able to distinguish and define: cf., for example, Not arrived. He arrived, where, although it is not known who arrived, but at the same time a particular person is thought male.
In the impersonal sentence, on the contrary, the subject cannot be distinguished and defined. It seems to dissolve in reality, and not allocated as a certain part and has no definite boundaries: compare, for example, It is necessary ... It is necessary ..., where the subject has a very obscure and elusive significance of the situation, a known situation that makes something necessary ( It is necessary to ! go there / to stay there / to do That - It is necessary to go there / stay there / do it , etc. ); cf. and It snows - It's snowing , where it is impossible to catch even this vague and undefined value.
English impersonal sentences differ from Russian impersonal sentences in that they always have a subject: cf. It is dark and "Dark"; It is getting dark and "It's getting dark "; It is necessary to go there and "You must go there ." However, this subject, as already indicated, does not designate any real subject: the elusive content that is contained in the subject (known situation, life situation), as it dissolves in the content of the predicate and cannot be isolated and considered independently. Such a subject can be called impersonal.
Note. Impersonal sentences with the subject in the English language arose in a relatively recent time. In any case, in the ancient texts there are impersonal sentences without the subject type "snows". One can think that the introduction of it as a subject is directly related to the decrease in the number of verbal forms of the face and number and the increase in their homonymy: the habit of using the subject in other cases is also transferred to these cases.
Thus, English impersonal sentences differ from Russian impersonal sentences in that in them impersonality is expressed not by the absence of the subject (as in Russian impersonal sentences) but in the semantic devastation of the subject or in his impersonality. To impersonal sentences are also types such as I t is useful Useful, It is necessary is necessary, usually followed by an infinitive or a subordinate clause with the conjunction That. English grammars usually say that the present subject in this case is the infinitive or subordinate clause, and it is the "empty word" preceding the subject. This it is usually called "is preceded by" (anticipatory) it and is distinguished from impersonal it. However, it is hardly true: "anticipating" it is the same impersonal it , being in the sentence the only subject, and the subordinate clause or infinitive is a known refinement, the development of the content of the predicate: is necessary , is useful, etc.
In the sentence “It is necessary to go there” the first part “It is necessary” informs about the necessity to do something. The content of this need must be specified. This concretization of the content of the predicate is either an infinitive or a subordinate clause. The latter, therefore, do not stand in the spotlight, they only give some clarification. This position is confirmed by the following comparison. It is not difficult to see the difference between the sentences “It is necessary to go there and t go there is necessary” (compare with Russian 'It is necessary to do this' and 'Make it necessary'); in the first case, the content of what is needed is disclosed, and in the second, the action “to go” is described, it is reported that it is necessary. In the first case, it is said that there is a need to do something, and in the second, that the commission of this action is a necessity. In other words, these sentences differ in value. The sentence “It is necessary to go there” corresponds with the sentence “I must go there”, where “go” is not in any way a subject, but is part of the predicate group, develops the content of the predicate.
In both sentences the infinitive reveals the content of the predicate, the subject here is “it”, which is only a formal support for the verb and does not add anything new to the content of the sentence.
Similarly, in the sentence "It is difficult to understand this", the impersonal "it" is also subject, and the infinitive explains, reveals what is difficult. Similarly, it is necessary to consider "it" in sentences such as "It is said that the meeting will not be held". Often the subject in such cases is considered to be "the meeting will not be held, and" it "is considered as a" pre-emptive "" it ", indicating the following subject as" That-Clause ". In reality, the so-called "That-Clause" has here the same character as the subordinate clause in the case of "They say that the meeting will not be held," i.e., reveals the content of the predicate (say).