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.
