The main verb is also called the lexical verb or the principal verb. This term refers to the important verb in the sentence, the one that typically shows the action or state of being of the subject

1.2. 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.⁸
The non-finite forms or verbals are four in number, they are: the infinitive, the gerund, the present participle, the past participle.
The verb in its finite form possesses the morphological categories of person 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 1st person, someone addressed by the speaker, addressee second person or someone/ something other than the speaker or the person addressed the third 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.⁹
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:
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).
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.¹⁰
Voice: active or passive. A distinction between active and passive is often called a distinction of voice. It offers different ways of focusing attention on various parts of information.
When you talk about the person or thing that performs an action, you use the active voice. Mr Smith locks the gate at 6 o’clock every night. The storm destroyed dozens of trees. I deny that, said Joan. We know you’ve been cheating us. Why have you done it? Thus, the active voice shows that the person or thing denoted by the subject of a sentence is the agent (the doer of an action) expressed by the predicate verb.
When you want to focus on the person or thing that is affected by an action, rather than the person or thing that performs the action, you use the passive voice. The gate is locked at 6 o’clock every night. Dozens of trees were destroyed. The news will be announced after dinner. The child knew that she was being praised. Nearly all the furniture will be taken out of the room. I was not allowed to chat. Trespassers will be prosecuted. The passive voice serves to show that the person or thing denoted by the subject of a sentence is not the agent (the doer of the action) expressed by the predicate verb but is the object of this action. The subject of the Passive verb does not act but is acted upon, it undergoes an action. To form the passive voice, all tenses use the corresponding active tense of BE + past participle. The chair was broken in the fight. Only transitive verbs can have a passive form.¹¹
Mood. A distinction (opposition) between indicative (for facts), imperative (for requests, instructions) and subjunctive (for non-facts, hypotheses, and suppositions) is usually called a distinction of mood.
The imperative is the same as the base form of verb. You use the imperative to ask or tell someone to do something, or to give advice, warnings, or instructions on how to do something. Start when you hear the bell. Don’t go so fast. Pass the salt. Hurry up!
There are few subjunctive forms in modern English, which usually finds other ways of indicating that the events being talked about are uncertain or hypothetical. There are two types of subjunctive:
Base of the verb for all verbs and all persons is used to express wishes. God save the Queen! Bless you! Long live the President! Heaven help us!
Were-subjunctive. The verb BE can use WERE for all persons in certain constructions.
If I were rich, I would change the world. If only I were young again. Suppose she were to win the championship.
1. Categories of person and number of the verbs serve to show the connection between the subject and the predicate of a sentence – the subject agrees with the predicate in person and number. Verb concord means the correspondence or ‘agreement’ between singular or plural subjects and their verbs (predicates). As there are few verb inflections in English, this only applies with BE, DO and HAVE and tenses using them, and the present simple tense of lexical (main) verbs. Problems arise where there is a conflict between grammatical and ‘notional’ number:
1) When the subject is a noun phrase (not a simple noun) the verb (predicate) should agree with the head. *This box of chocolates is for you. What was the cost of the tickets? Buying all those tickets was extravagant. But if the head is felt to be unimportant (a number of) the verb may agree with another noun, particularly if this noun is closer: A number of pupils have chosen this new course.
2) Noun phrases involving times and prices are usually felt notionally to represent single units. They take single verbs: Five pounds is cheap. Twelve days is too long.¹²
3) Some expressions joined by and have singular determiners, verbs and pronouns. This happens when the two nouns are used together so often and co-ordinate subjects felt to constitute single units that we think of them as a single idea. This gin and tonic isn't very strong, is it? 'War and Peace' is the longest book I’ve ever read. Decline and Fall is a great book. War and Peace is written by L. Tolstoy. The bread and butter was too thin.
4) But a single noun phrase with a mass (non-count) noun that in fact has double reference (Australian butter and New Zealand butter) can take plural verb. Australian and New Zealand butter come in refrigerated ships.
5) Plural names of countries (as well as plural names of organisations) usually have singular verbs and pronouns. The United States is anxious to improve its image in Latin America. Consolidated Fruitgrowers has just taken over Universal Foodstores.
2. Categories of tense and aspect
a) Difference between the two present perfect tenses
Compare:
1) Susan has been cooking. Susan has been cooking dinner. Susan has been cooking this afternoon. (All these statements emphasise activity, they might be offered as reasons why she has not had time to do something else).¹³
2) Susan has cooked the dinner This stresses achievement – the dinner which is now ready.
Simple Achievement
Progressive Activity
I have visited Ireland / twice/ many times -prior
He has drunk the wine. There is none left.
I have run / all the way here / six miles. But not: I have run.
Susan has learnt Arabic since 1987. A complete achievement in the period since 1987. She didn’t know Arabic before, and now she does.
Peter has won. i.e. in a race, match, etc. Here unusually, a verb alone stands for the complete achievement.
What have you done about that job you wanted? (Have you applied? etc.)
I have been visiting Ireland (recent: this tense is not possible with twice, etc)
Tom has been drinking / the wine. (In both cases there may or may not be some wine left.)
I’ve been running. (That’s why I’m hot and tired.)
Susan has been learning Arabic since 1987. (Maybe she is still learning.)
Peter has been winning a lot of prizes. (Recent repeated activity. A verb to win, by itself, is a verb of achievement rather than activity.)
What have you been doing since I last saw you?
b) Difference between the past simple and the past perfect
The use of past adverbials (yesterday, last summer, in 1963, ago) normally makes past simple obligatory. Compare: We left Bristol five years ago (single action). We have lived in Bristol for the past three years (durative activity). Perfect adverbials (already, for, just, since yet) usually require perfect tenses. Karen has just passed her exam. Have you finished your translation yet?
If there are no obviously time-linked adverbials, the present perfect goes with still present time. Compare: Queen Victoria reigned for over sixty years. (Her reign is past.) Did you have a happy childhood? (said to an adult.) I saw Henry in New York. (I’m now somewhere else.) My father lived here all his life. (He is dead now.) He has lived here all his life. (He is still alive.)¹⁴
c) Difference between the past simple and the past progressive
A common contrast between the present simple and the present progressive is between habits or repeated actions (simple) and an action of limited duration at the moment of speaking (progressive): We were sitting in the kitchen when we heard the explosion. Jack arrived when the children were having their bath. I was smoking a cigarette (actual past moment) when Tom walked in (single action). I smoked 30 cigarettes a day in those days (past habit), but I was not smoking with him. I knew he didn’t like it (temporary activity.) We lived in Chicago (long-term state of affairs). They were living in a hotel (temporary activity.) The past progressive is often used to refer to a temporary situation: He was working at home at the time. Bill was using my office until I came back from America.
d) The past perfect tense is marked for past and perfective. The combination implies some measure of achievement before some past point. It refers to pre-then, not to pre-now as the present perfect does. By 2004 Paul had had enough. He had visited America twenty times in the previous thirty years. She had never, at that time, met a foreigner. In Ukrainian, the need to distinguish some pre-past and the past is not so keenly felt. ‘The past simple’ is sufficient in both cases. In English, the past perfect is only obligatory in contexts where perfectiveness, not mere prior happening, must be stressed. This is usually in subordinate clauses (e.g., in some conditionals, some reported speech, some time clauses, and with some adverbials). A number of adverbials establish a past point to which prior achievement is related (at that time, by then, up till then).
e) The main ways of talking about the future
Present simple. Uncle Ben leaves tonight. His train leaves at 10 pm. We have a meeting every day next week. According to the brochure, we stay in Rome for five days and then fly to Athens. This usage often feels formal and impersonal. It is not very common, except with travel arrangements and fixed timetables.¹⁵
Present progressive. What are you doing tomorrow? We’re having lunch with the Smiths. Monica and Adrian are getting married in August. It is a very common usage: an arrangement already exists now for the future. It is sometimes interchangeable with the model: going to + infinitive because arrangement and decision overlap.
Going to + infinitive. I’m staying at the Ritz (suggests I have booked a room), whereas I am going to stay at the Ritz emphasizes my decision and intention.
Will/shall. With future reference, this tense is concerned either with ‘pure future’ and prediction or with volition, which means a decision now at this moment. I’ll be 21 next month. (‘pure future’). You’ll be cold in Scotland in January (prediction). Oh well, I’ll wait till the summer. I’ve spilt my coffee – I’ll get a cloth (decision now).
Will/shall be + ing. This time next week I’ll be sunbathing in Florida. The progressive tense puts emphasis on the activity rather than on volition, so this form implies a predictable future.