Modal verbs (also known as modals and modal auxiliary verbs) are verbs that are used to provide additional information about the main verb. They are known as a type of auxiliary verbs. There are nine modals in the English language:

Here are some modals in action:

Modals are used for communicative purposes:

Adverbs are words that can modify a verb, an adjective, another adverb, or a full sentence. Adverbs modify verbs to show how an action happened.

As you can see on the list, adverbs express different contexts. We also have the same function with modal verbs. Both are used to talk about moods. That is why some learners may be confused about when to use them. We will cover the areas where we can use either an adverb or a modal verb to convey our desired messages including:

We can use adverbs (like possibly, likely, hopefully) and modals (such as can, could, may, and might) to discuss something we are unsure about. Take a look at the following examples:

When we want to make any predictions, we can use modals (such as will and would) and adverbs (like soon). Have a look:

We also use modals (like should) and adverbs (such as seemingly and presumably) to talk about a declaration without firm proof. For example:

Modals (such as will and would) and adverbs (like willingly and voluntarily) show willingness and unwillingness for something. Here are some examples for clarity:

We also use both modals (such as must and shall) and adverbs (like ungently or necessarily) to discuss things that need to be done. Look:

Habits are actions that are done routinely. We can use modals (like would and will) and adverbs (such as usually, routinely) to talk about these habits.

There are times when we cannot use adverbs to convey the same meaning as modals:

We use modal verbs can and could to talk about powers and skills possessed to do a certain action. We cannot use adverbs to convey the same meaning. Have a look:

We use can, could, and may to give or ask for permission. May and could are more formal and politer. We cannot use adverbs to convey this message. For example:

We often use can, could, should, and might to offer solutions or give someone a piece of advice. Adverbs, unfortunately, are unable to convey meaning in this context.

Can, could, will and would are used to request something from someone. We cannot use adverbs to do so.

Adverbs are capable of appearing in different positions in a sentence. They must be close to the words they are modifying, which could be at the beginning, in the middle, or at the end of a sentence. Have a look:

Unlike adverbs, modals are always in one place and will not change their position. They always come before the main verb. Look:

Modals can be used to make negative sentences. To do so, we add ‘not’ to the head of the sentence which is the modal verb. Watch:

To make a negative sentence, we can use negative adverbs such as 'no', 'not', 'never', and 'never'.

Modals must be used with the main verb and cannot be used alone (unless it is in a short answer like “I can.”).

Modals also cannot be used with another modal in the same clause.

Adverbs are not bound to numbers in a clause and you can use as many adverbs as desired to convey the meaning you are after. However, be careful using too many adverbs may make your sentences chunky and hard to understand.