Auxiliary verbs are those which have no lexical meaning of their own and are used as form-words, thus having only a purely structural function in the sentence. They are used to make up analytical forms and are always accompanied by notional verbs, i. e. these verbs are parts of analytical forms of the verb, or rather, grammatical word-morphemes. Here belong such verbs as be (in Continuous tenses and Passive Voice), do (in negative and interrogative forms of Indefinite tenses), have (in Perfect tenses), shall and will (in Future tense), should and would (in Future in the Past and Subjunctive).
Linking verbs have partly lost their lexical meaning and are used as part of a compound nominal predicate.
The doctor was quite young.
The main lexical meaning of this kind of predicate is expressed by the predicative (a noun, an adjective, a verbal, etc.).
N o t e. In different contexts the same verb can be used differently (as a notional verb, an auxiliary verb or a linking verb).
No one was there to meet her. (notional verb) She was not very young, (linking verb) She was coming, (auxiliary verb)
Modal verbs make up a special group of verbs: they cannot be used independently unaccompanied by notional verbs, though they have a lexical meaning of their own. The meaning of action or process common to all verbs is very scarce in modal verbs and is dominated by the meaning of modality, i. e. of the ability, necessity or determination to perform an action denoted by a notional verb. They are used as part of a compound predicate. Here belong such verbs as can, may, must, need, shall, will, should, ought.
(3) According to their association with the subject and the object of the action all verbs are divided into transitive and intransitive.
Most verbs are associated with two nouns (or noun-equivalents) denoting the subject and the object of the action expressed by the verb.
Some verbs, however, are associated only with nouns (or noun-equivalents) denoting the subject of the action.
In the sentence "He entered and greeted them" the verb greeted is associated with the pronoun he denoting the subject of the action of greeting and with the pronoun them denoting the object of the same action. The verb entered is associated only with the pronoun he denoting the subject of the action.
In the sentence "She looked at them" the verb looked is also associated with the pronoun them denoting the object of the action of looking. But there is some difference between the two verbs in the word-groups greeted them and looked at them. The verb look is associated with the word denoting the object by means of the preposition at.
Verbs that are, connected with their object words directly are called transitive verbs: in other words, transitive verbs are those verbs which take a direct object.
I have enjoyed the game.
All other verbs are called intransitive. Such verbs as live, think, sleep, stand, etc. are intransitive.
There are verbs which can be used either with or without a direct object (the so-called transitive-intransitive verbs); here belong such verbs as read, write, see, hear, etc.
There are other verbs whose primary meaning is transitive and whose secondary meaning is intransitive;- Here belong such verbs as sell, wear, add, etc.
They sell books. — This book sells well.
There are also verbs whose primary meaning is intransitive and whose secondary meaning is transitive. Here belong such verbs as run, fly, sail, work, walk, etc.
I can't run as fast as you.—Who is running the show?
N o t e. There are verbs which in different contexts can be transitive or intransitive. It is impossible to say which meaning is primary and which is secondary. Here belong, for instance, such verbs as open, move, turn, change, etc, She opened the door. —The door opened.