A modal verb (also modal, modal auxiliary verb, modal auxiliary) is a type of auxiliary verb that is used to indicate modality. The use of auxiliary verbs to express modality is a characteristic of Germanic languages. In the English language, a modal verb is an auxiliary verb that can be used to change the grammatical mood of a sentence. The key way to identify a modal verb is by its defectiveness (they have neither participles nor infinitives).
Exercise 1. Exercise 2.
!Note The modal auxiliary verbs are always followed by the base form. The verb used to, which is explained here, can also be used like a modal verb. We use it for: CAN Ability / Possibility Inability / Impossibility Asking for permission Request COULD Asking for permission. Request Suggestion Future possibility Ability in the past MAY Asking for permission Future possibility MIGHT Present possibility Future possibility MUST Necessity / Obligation Prohibition SHALL Offer Suggestion Asking what to do SHOULD Saying what's right or correct Recommending action Uncertain prediction OUGHT (TO) Saying what's right or correct WILL Instant decisions Offer Promise Certain prediction WOULD Asking for permission Request Request Making arrangements Invitation Preferences