“Writers should learn to properly use auxiliary modal verbs.”
Auxiliary verbs are also known as helping verbs.
I am working = Working is the main verb. Am is the auxiliary.
She has arrived = Arrived is the main verb. Has is the auxiliary.
Do you drive? = Drive is the main verb. Do is the auxiliary.
Auxiliary verbs come before the main verb (lexical verb) in a sentence. They determine mood, tense, or aspect of another verb the sentence. Together the helping verb and the main verb form a verb phrase.
Modal Auxilliary Verbs
First, they can be used when we want to say how sure we are that something happened / is happening / will happen. We often call these ‘modals of deduction’ or ‘speculation’ or ‘certainty’ or ‘probability’.
We use ‘can’ and ‘could’ to talk about a skill or ability.
Obligation and Advice
We can use verbs such as ‘must’ or ‘should’ to say when something is necessary or unnecessary, or to give advice.
We can use verbs such as ‘can’, ‘could’ and ‘may’ to ask for and give permission. We also use modal verbs to say something is not allowed.
We can use ‘will’ and ‘would’ to talk about habits or things we usually do, or did in the past.