Be, do, have as a main verbs.

Main Verbs: Definition and Examples

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. Main verbs can stand alone, or they can be used with a helping verb, also called an auxiliary verb.

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Helping verbs do just what they sound like they do—they help! Different helping verbs help or support the main verb in different ways. For instance, they can show tense (which indicates when an action happened), ability, intention, or possibility. The primary helping verbs are to be, to do, and to have. To better understand how helping verbs support main verbs, consider the examples below:

I am driving to the beach.

Here, the auxiliary verb “am” (a form of to be) lets the reader or listener know that the main verb in the sentence—in this case, “driving”—is happening continuously in the present. Different forms of to be could be used as a helping verb to explain when the driving is occurring (e.g., was driving, will drive, or had been driving).

I did empty the trash.

In this sentence, the helping verb “did” (a form of to do) emphasizes the main verb, which is “empty.” For instance, if your mother instructed you to take out the trash and you already did it, you wouldn’t likely say, “I emptied the trash.” Instead, you would say, “I did empty the trash!”

I had seen the movie before.

Here, the auxiliary verb “had” (a form of to have) is used to express the past perfect tense, which indicates that the action of the sentence occurred at an earlier time in the past. For example, if someone told you they “saw” a movie, you may think they just finished watching it. If they say they “had seen” it, however, you would know that they went to the movies at some earlier time.

Main Verbs as Linking Verbs

As mentioned previously, main verbs aren’t always action verbs. Sometimes they simply express a subject’s state of being. In these cases, the main verbs are referred to as linking verbs since they link the subject to information concerning its state of being (referred to as a subject complement). Consider the examples below:

As a toddler, Susan was adorable.

Note that the main verb “was” does not express Susan’s actions but her state of being (i.e., adorable).

Jennifer is a nurse at the local hospital.

Here, the main verb “is” links the subject (Jennifer) to its complement, “a nurse.”

Linking Verb Tip: It may be helpful to think of a linking verb as an equal sign. If you can substitute an equal sign for the main verb in a sentence, and it makes sense, then the main verb is a linking verb.

Transitive and Intransitive Main Verbs

Main verbs can be transitive or intransitive. Transitive verbs take a direct object while intransitive verbs do not. Transitive verbs require direct objects to receive their action. Intransitive verbs, however, can express action without a direct object, and as a result, they can end a sentence without the sentence sounding incomplete. Consider these examples:

Transitive Verbs:

• They attended the party.
• Jenny fed the cat.
• Fred loves cake.

Intransitive Verbs:

• The wind blew .
• John laughed .
• The keys disappeared .

Since intransitive verbs do not take a direct object, they are often found at the end of a sentence. In many cases, however, an intransitive verb may be followed by another part of speech, such as an adverb or prepositional phrase. Look at the sentences below for an illustration:

The wind blew fiercely.

Here, “fiercely” is an adverb that describes how the wind blew.

John laughed for what seemed like an hour.

In this sentence, “for what seemed like an hour” is a prepositional phrase that explains how long John laughed.

The keys disappeared yesterday.

Here, “yesterday” acts as an adverb that describes when the keys disappeared.

Some main verbs can be transitive or intransitive depending on how they are used. Look at the sentences below.

The teenage boy eats voraciously.

The teenage boy eats five meals a day.

In the first sentence, “eats” acts as an intransitive verb and is followed by “voraciously,” an adverb that describes how the teenage boy ate.

In the second sentence, “eats” acts as a transitive verb and is followed by the direct object “five meals,” which explains what the teenage boy ate.

Understanding the different types of main verbs and how they function makes identifying them in a sentence much less challenging. 

Source : https://www.grammarly.com/blog/main-verb/