Full modal verb

From Teflpedia

A full modal (auxiliary) verb, is a verb (specifically a modal verb, and an auxiliary verb) used with a catenated verb to express possibility or necessity[1] along with concepts such as obligation, permission, inevitability etc. They are used to express the speaker's opinion of a subject and thus to affect the modality of a sentence.

The full modal verbs in English are shown in the table below:

Present tense Negative contraction(s) Past tense Negative contraction Fundamental meaning (positive) Meaning (negative) Notes
can cannot, can't could couldn't Ability Inability
will won't, 'll not would wouldn't Certainty Negative certainty
may ?mayn't might mightn't possibility erm... mayn't is rare.
shall shan't should shouldn't obligation negative obligation
must mustn't must mustn't obligation prohibition Invariant preterite.

Grammatical properties[edit]

As a group the full modal verbs have a number of properties which separate them from lexical verbs and, to an extent, from primary auxiliary verbs.

  • They can be negated with not. In other words we can say "will not" but we cannot say *"run not"—at least in modern English.
  • They have no infinitive, e.g. we can't say *"to can"; see infinitive of a modal verb.
  • They have weak forms, especially in the negative.
  • They cannot co-occur in sentences. We cannot say, *"This may will happen".
  • They can be used to form polar questions. (Yes/no questions).
  • They can be used in ellipsis. In answer to the question "Can you swim?" the answer "Yes, I can" is understood to mean "Yes, I can swim."
  • They are not conjugated or changed in any way. That means they have no third person "s", no past participle and no present participle/gerund "-ing" form.
  • They are followed by the bare infinitive of another verb. That means they are not followed by a to infinitive.
  • The New Oxford Dictionary of English