Introduction Role of Grammar compared with other linguistic disciplines

3. Grammatical categories of verbs
The finite verbs in the contrasted languages has six common morphological categories which are realized partly with the help of synthetic (simple) means (by inflections) and partly through different analytical (compound, consists of at least two verbal elements) forms. Thus the categories of person and number are realized in both contrasted languages synthetically, whereas the category of tense is realized both synthetically and analytically. Verbs present a system of finite and non-finite forms.

1. 
   The non-finite forms (or verbals) are four in number, they are: the infinitive, the gerund, the present participle, the past participle.
   
2. 
   The verb in its finite form possesses the morphological categories of person (особа), number (число), tense (час), aspect (вид), voice (стан) and mood (спосіб).
   

Category of person expresses the relation of the action and its doer (agent) to the speaker, showing if the action is performed by the speaker (1^st person), someone addressed by the speaker, addressee (2^nd person) or someone/ something other than the speaker or the person addressed (the 3^rd person).
Category of number shows whether the action is performed by one or more than one persons or non-person (for to be: am/is/are; was/were). We find three persons and two numbers in finite verbs.
The category of tense in English (as well as in Ukrainian and Russian) expresses the relationship between the time of the action and the time of speaking. Time and tense are not the same thing. ‘Time’ (consisting of past, present and future) is a concept; tense is a grammatical device. Unlike Ukrainian, where there are three tenses: Present, Future and Past, English has two distinct tense forms: Present tense and Past tense, though plenty of ways of talking about future. Besides, there is one more tense in English, the so-called future in the past, when a future situation is viewed from some moment in the past.
In English, the present simple is the unmarked tense. This means it is used for very general time where specific marking for non-present time is unimportant and so unnecessary. To put this another way, any period that includes the moment of speaking (whether extending into the past or the future) can be regarded as present time and use a present tense. The past simple, marked usually by inflection, is a marked tense. Conceptually, the present tense form ties the situation described closely to the situation of utterance: I live here now. The past tense form makes the situation described more remote from the situation of utterance: I lived there then. The situations in the future are treated differently. They are inherently non-factual, but can be considered as either relatively certain (i.e. perceived as close to happening) or unlikely or even impossible (i.e. perceived as remote from happening). The verb form that is traditionally called ‘the future tense’ is actually expressed via modal verb which indicates the relative possibility of an event: I will live here.
Aspect – perfective or progressive. In order to talk about aspect, we have to look inside the situation.
In terms of its internal dimensions, a situation may be represented as fixed or changing, it may be treated as lasting for only a moment or having duration, and it can be viewed as complete or as ongoing. These are aspectual distinctions. The grammatical expression of aspect is accomplished via the perfect or progressive forms of the verb. If we want to emphasize that the action or state:

1. 
   Is in some way completed or achieved, though still relevant, this is called perfective aspect and is indicated by the use of HAVE + past participle of the lexical verb. I have written the letter (so now I can send it).
   
2. 
   Is/was in progress or temporary or uncompleted, this is called progressive aspect and is indicated by using BE + present participle. I am/was writing the letter.