What Is Their Main Difference?
Modal verbs (also known as modals and modal auxiliary) are a group of verbs that give additional information about the function of the main verb. Modal verbs are a type of auxiliary verbs. We have nine modals in English:
Here are some examples so we can see modals in action:
Auxiliary verbs (also called the helping verbs) are verbs that are paired with a main verb to create tenses and voices. We have four auxiliary verbs in English language:
In the following examples, we have the auxiliary verbs 'do' and 'be':
'Will' is a modal auxiliary verb. There is confusion around it as it functions like an auxiliary, but it is not an auxiliary verb. 'Will' is sometimes counted as an auxiliary verb to make it easier for learners to understand when it expresses the future tense.
At this pace, we
With Main Verbs
Both auxiliary verbs and modals must be used with a main verb and cannot be used alone (unless there is a short answer such as "I can." and "I am."). Have a look:
shall him a letter.")
has been when they called.")
Negation and Questions
Much like auxiliary verbs, modals can create a negative sentence. In this case, we add 'not' to the modal or the auxiliary verb. For example:
We can also ask questions using modals and auxiliary verbs. To do so, we invert the modal or the auxiliary. Look:
When our sentence consists of a modal verb and more than one auxiliary verb, the head of the sentence will be the modal verb and when making the sentence negative, we add 'not' to the modal verb. Watch:
Modals are used for communicative purposes such as:
- talking about possibilities, probabilities, etc.
- asking for advice, permission, etc.
- talking about habits
Here, we are talking about a possibility.
Here, we are suggesting something.
Auxiliary verbs, however, are used to help express the main verb's:
Here, we have the auxiliary verb 'be.'
Here, we have the auxiliary verb 'have.'
Modals cannot be conjugated, and the only way to conjugate them is to use their base form. Auxiliary verbs, however, can be conjugated. They change their appearance according to the subject or tense. Take a look at the following examples:
musted be here on time.")
With Other Verbs
Modals can be used with as many auxiliary verbs as possible in one sentence:
'Should' is a modal verb and 'have' is an auxiliary verb.
You can also use several auxiliary verbs in one sentence:
However, we cannot use multiple modals in one sentence. You can only use one:
will could help you.")