Forms of be can do two very different jobs in English. In The room is quiet, is connects the room with a description of it. In The guests are waiting, are helps form the verb phrase are waiting.
The first is a linking verb. The second is an auxiliary verb, also called a helping verb. The words may look identical, but their grammatical roles are different.
Linking Verb vs. Auxiliary Verb: What Is the Difference?
A linking verb functions as the main verb and connects the subject with information about that subject.
Hannah is a veterinarian.
Is links Hannah with a veterinarian, which identifies her.
An auxiliary verb works within a larger verb phrase and helps form a grammatical construction or add meaning.
Hannah is examining the dog.
Is helps form the continuous verb phrase is examining.
The basic difference is:
Linking verb: connects the subject with a subject complement.
Auxiliary verb: helps form a larger verb phrase.
The distinction matters most with forms of be, because am, is, are, was, were, be, being, and been can appear in either role.
Linking Verbs and Auxiliary Verbs at a Glance
| Feature | Linking Verb | Auxiliary Verb |
|---|---|---|
| Main job | Connects the subject with information about it | Helps form a larger verb phrase or adds grammatical meaning |
| Role | Functions as the main verb | Works with another verb |
| What commonly follows | A subject complement | Another verb form |
| Main area of overlap | Forms of be | Forms of be |
| Example | The road is narrow. | The crew is repairing the road. |
This gives you the basic pattern, but a few sentence types need a closer look before you can classify the verb confidently.
Why Forms of Be Cause the Most Confusion
The main overlap between linking and auxiliary verbs comes from be.
Compare:
The students are ready.
Are is the linking verb. Ready describes the students.
The students are preparing the room.
Are is an auxiliary. It helps form are preparing.
The same contrast appears in the past:
The hallway was dark.
Was links the hallway with the description dark.
The staff was cleaning the hallway.
Was helps form was cleaning.
A form of be therefore cannot be classified from the word alone. Its job depends on the structure around it.
How a Linking Verb Works
A linking verb connects the subject with a subject complement that identifies, classifies, or describes the subject.
Elena became the department head.
The department head identifies Elena.
The pavement looks slippery.
Slippery describes the pavement.
Their explanation seems plausible.
Plausible describes their explanation.
The complement points back to the subject rather than functioning as a direct object.
How an Auxiliary Verb Works
An auxiliary helps another verb form part of the verb phrase.
With be, the two most important patterns for this comparison are the continuous and the passive.
Continuous:
The engineers are testing the system.
Are helps form are testing.
Passive:
The system was tested yesterday.
Was helps form was tested.
Other auxiliaries include forms of have and do, along with modal verbs such as can, might, should, and will.
Leah has completed the survey.
Did Aaron submit the form?
The weather might improve later.
Here, the useful distinction is simply that an auxiliary contributes to a larger verb phrase rather than linking the subject directly with a complement.
A Sentence Can Contain Both an Auxiliary Verb and a Linking Verb
Linking and auxiliary verbs are not mutually exclusive at the sentence level. One sentence can contain both.
Maya may be tired.
May is a modal auxiliary.
Be is the linking verb connecting Maya with tired.
Another example:
The neighborhood has become quieter.
Has is the auxiliary helping form the perfect construction.
Become is the linking verb connecting the neighborhood with quieter.
And:
The results might seem surprising.
Might is the auxiliary, while seem is the linking verb.
The labels apply to the individual verbs and the jobs they perform, not to the sentence as a whole.
Does Another Verb After Be Always Make It an Auxiliary?
A clear continuous construction is easy to recognize:
Chloe is writing the summary.
Is is auxiliary because is writing forms a continuous verb phrase.
A clear passive is also straightforward:
Chloe was interviewed by the research team.
Was helps form the passive was interviewed.
But an -ed or -en form after be does not always function as part of a passive verb phrase.
Chloe is interested in astronomy.
Here, interested describes Chloe’s state. In the ordinary reading, it behaves like an adjective complement, and is functions as a linking verb.
Another example:
The children are excited about the trip.
Excited can describe the children’s state rather than an event being done to them.
So the shape be + past-participle-looking word is not enough by itself. You need to consider whether the following word is functioning verbally or adjectivally in that sentence.
Some Be + Past Participle Sentences Can Have More Than One Reading
Context sometimes matters.
Consider:
The door was closed.
This can describe a state:
The door was in a closed condition.
In that reading, closed behaves much like an adjective describing the door.
The same words can also describe a passive event:
Someone closed the door.
Compare the contexts:
When we arrived, the door was closed.
The focus is naturally on the door’s state.
The door was closed by the security guard at nine.
The by phrase makes the passive event reading clear.
Some cases lie between a clear adjective and a clear verbal passive, and grammatical analyses may differ in borderline examples. Context is more useful than forcing every isolated be + participle sequence into one category.
Can an Auxiliary Verb Appear Without a Main Verb After It?
Yes. This is why the rule “an auxiliary must always have another verb immediately after it” is too absolute.
Can Marcus swim?
Yes, he can.
The verb swim is not repeated in the answer, but its meaning is understood.
The same happens here:
I haven’t finished, but Ava has.
Has represents the understood phrase has finished.
The missing part of the verb phrase can be left out when the context makes it clear.
That does not turn can or has into linking verbs. Their auxiliary function is still recoverable from the larger sentence or conversation.
Are Have and Do Ever Linking Verbs?
The primary auxiliaries have and do can also function as main verbs, but that is a different issue from being a linking verb.
Compare have:
Daniel has completed the inspection.
Has is auxiliary.
Daniel has three bicycles.
Has is the main verb expressing possession.
It does not link Daniel with a subject complement.
Now compare do:
Did Priya call the office?
Did is auxiliary.
Priya did the calculations herself.
Did is the main verb.
Again, it is not linking.
So the important overlap between linking and auxiliary functions is mainly the verb be. The fact that have and do can be either auxiliaries or main verbs is a separate distinction.
What About Verbs Such as Look, Feel, and Taste?
Verbs such as look, feel, smell, sound, and taste can function as linking verbs, but they do not become auxiliary verbs in those uses.
The fabric feels smooth.
Feels is linking.
The curry tastes mild.
Tastes is linking.
These verbs can also have non-linking main-verb uses:
Nora felt the fabric.
The chef tasted the curry.
Here, felt and tasted are still main verbs. They have changed from linking uses to other main-verb uses, not to auxiliary verbs.
That helps keep three different ideas separate:
- linking verb
- auxiliary verb
- other main-verb use
How to Tell a Linking Verb From an Auxiliary Verb
When a form of be causes confusion, look at what comes after it and how the pieces relate.
The audience was silent.
Silent describes the audience. Was is linking.
The audience was applauding.
Was applauding forms a continuous verb phrase. Was is auxiliary.
The audience was photographed after the event.
Was photographed forms a passive verb phrase. Was is auxiliary.
A useful way to check is to ask:
- Does the form of be connect the subject with something that identifies or describes it?
- Or does it help form a continuous or passive verb phrase?
For straightforward sentences, that distinction usually settles the question.
If a past participle follows be, look more carefully. It may be part of a passive construction, an adjective describing the subject, or occasionally a borderline case where context matters.
Linking Verbs vs. Auxiliary Verbs: Examples Compared
These pairs show how the same form of be can perform different jobs.
Is
The conference room is available.
Is is linking.
The receptionist is checking the schedule.
Is is auxiliary.
Are
The instructions are clear.
Are is linking.
The technicians are installing the software.
Are is auxiliary.
Was
The garden was beautiful in spring.
Was is linking.
The gardener was trimming the hedge.
Was is auxiliary.
Were
The roads were icy before sunrise.
Were is linking.
The crews were treating the roads with salt.
Were is auxiliary.
Been
The office has been quiet all morning.
Has is auxiliary. Been is the linking form of be, connecting the office with quiet.
The office has been renovated recently.
Has helps form the perfect construction, while been participates in the passive verb phrase been renovated.
The same form can therefore require a different analysis depending on the structure around it.
A linking verb connects the subject with information about that subject. An auxiliary verb helps form a larger verb phrase or contributes grammatical meaning. Forms of be create most of the overlap, and the difference becomes much clearer when you focus on the job the verb is doing rather than the word itself.
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