Quasi-modal Verbs versus Modal Verbs
Just as pronouns are a subcategory of nouns, quasi-modal verbs are a subcategory of modal verbs. Quasi-modals resemble modals in that quasi-modal verbs also do not reflect grammatical number. For example:
You need to study for the test. (correct)
He needs to study for the test. (correct)
You should study for the test. (correct)
He should study for the test. (correct)
*He should study for the test. (incorrect)
You ought to study for the test. (correct)
He ought to study for the test. (correct)
*He oughts to study for the test. (incorrect)
Quasi-modals also lack tensed (past, present) and nontensed (infinitive, present participle, past participle) forms. For example:
- Base – Infinitive – Present Tense – Past Tense – Present Participle – Past Participle
- eat – to eat – eat, eats – ate – eating – eaten
- could – *to could – could, *coulds – *coulded – *coulding – *coulden
- ought to – *to ought to – ought to, *oughts to – *oughted to – *oughting to – *oughten to
Quasi-modal verbs differ from modal verbs in form. While full modals are single words, quasi-modals consist of either a verb plus a preposition functioning as a particle or a verb plus an adverb. For example:
- ought to, used to = verb + preposition [particle]
- would rather, had better = verb + adverb
Similar to phrasal verbs, quasi-modals are periphrastic modal auxiliary verbs. Periphrasis, as defined by the Oxford English Dictionary, is "a phrase of two or more words that together perform a single grammatical function that would otherwise be expressed by the inflection of a single word." Quasi-modals, unlike modals, consist of two elements. However, quasi-modal verbs otherwise function identically to full modal verbs.
Note, however, that the quasi-modal verb ought to sometimes lacks a prepositional particle in negative and interrogative constructions. For example:
- He ought to buy a new car.
- He ought not buy a new car.
- Ought he buy a new car?
An asterisk * indicates an incorrect form.