Modal Verbs

All the auxiliary verbs except be, do and have are called modals. Unlike other auxiliary verbs modals only exist in their helping form; they cannot act alone as the main verb in a sentence.

Be, do, and have also differ from the other auxiliaries in that they can also serve as ordinary verbs in a given sentence.

Modal verbs are:

• Can: expressing ability or possibility. Asking for permission. Request.
• Could: Asking for permission. Request. Suggestion. Future possibility. Ability in the past.
• May: Asking for permission and Future possibility.
• Might: Present possibility and future possibility.
• Must: Necessity / Obligation and prohibition.
• Ought to: Saying what’s right or correct.
• Shall: (More common in the UK than the US)Offer, suggestion and asking what to do.
• Should: Saying what’s right or correct, recommending action.
• Will: Instant decisions, offer, promise, certain prediction
• Would: Asking for permission, request, making arrangements, invitation, preferences