Verb is a broader term because it cannot be defined with respect to one function like noun and pronoun. It sometimes denote action, like; play, hit, smell etc, and sometimes it stands for a copula like; seem, be or taste etc. Copula is that form of the verb which doesn’t stand for action. Anyway, the verb may be anything that stands for certain sort of activity in a sentence, or other way round which doesn’t act like subject (actor) or object (patient). Verb is an integral part of a sentence and sometimes gives complete meanings on its own in imperatives, like, sit, speak, come, go etc.
Forms of verb
Verb has six inflectional forms
Tensed and non tensed forms
Since tense means time, so tensed form of the verb is that inflectional category which alone and without using auxiliary, tells us about the time whether it is present or past, e.g. present (go) is tensed form because it alone tell us that the sentence is in present time, like, “OK, I go to fetch it”. Whereas past participle (gone) gives no information about time unless any auxiliary is used with it, like, has gone (present time) and had gone (past time) etc hence it is non-tensed form.
So in short tensed form is the form of the verb which gives information about time and non tensed form is the form of the verb which doesn’t give us any information about time unless any auxiliary is used with it.
Tensed forms are: Present form (go), Past form (went) and 3rd person singular form (goes).
Non tensed forms are: Past participle form (gone), Present participle (going) form and Base form (to go).
There are two further categories of verb;
Tense, as defined above is the verbal action in relation to time whereas aspect is related to the manner of verbal action. It means whether the verbal action is completed or it is in progress. In case of completion the auxiliary verb [have] and its inflectional forms are used whereas in case of being in progress be form shall be used. Look at the following examples.
In first sentence the verbal action (enjoying) is in progress whereas in the second example it is complete.
Be-form and copulative verbs
Be is the basic word for is, am and are so they all are called be-forms. Their past, past participle and present participle forms are same as explained under.
Forms of be
There are two forms of subject; Actor and non-actor. Actors are those subjects which denote action, like, “he writes me every month”. Here [he] is actor because it does the action of writing. Whereas non actors are those subjects which do not indicate action, like; “he seems ill”, “he is honest” etc. Here [he] which is subject in both sentences is not doing any action, and copulative verbs are always used with non-actor subjects because they themselves don’t show any action. Copulative verbs are; is, am, are, was, were, seem, taste etc.
Note: in all the above examples italicized verbs don’t indicate action hence they are copulative verbs are copulas.
Operators or Auxiliaries
Operators or auxiliaries are those verbs which are also called helping verbs. They are used with the main verb. There are three auxiliaries, like; be, have, and do. The rests are their forms. Like;
Be, is, am, are, was, were
Have, has, had
Do, does, did
Remember, when be-form is used with main verb like “he is responding positively” it is not called copulative verb because the subject [he] is actor and in copulas no other verb is used. Similarly have here is perfect have because it indicates that the verbal action has been done. And whenever have is used without any main verb, like, “I have a fever” it is not auxiliary because it doesn’t indicate perfection of verbal action rather no verbal action at all. And in case of do the situation is just the same. So in short we can say that operator or auxiliaries are only used with main verb.
Examples (the italicized words are operators or auxiliaries)
Modal operators are those operators which have only one or two tensed forms (present and past). They are also called modal verbs or modals in short.