Full modal verb
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 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|
|will||won't, 'll not||would||wouldn't||Certainty||Negative certainty|
|may||?mayn't||might||mightn't||possibility||erm...||mayn't is rare.|
- 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.