Modal verbs

Modal verbs are used to show the speaker’s attitude toward the action or state indicated by the infinitive, i. e. they show that the action indicated by the infinitive is considered as possible, impossible, probable, improbable, obligatory, necessary, advisable, doubtful or uncertain, etc. The modal verbs are: can (could), may (might), must, should, ought, shall, will, would, need, dare. The modal expressions to be + Infinitive and to have to + Infinitive also belong here.
Modal verbs are called defective because all of them (except dare and need) lack verbals or analytical forms, i. e. modal verbs cannot derive infinitives, gerunds or participles, nor can they produce any compound tenses (Continuous, Perfect, Perfect Continuous), analytical forms of the Subjunctive Mood or the Passive Voice.
Modal verbs do not take – s in the third person singular.
They also have the following peculiarities:
1. All of them (except ought and sometimes dare and need) are followed by the bare infinitive (infinitive without the particle to).
E. g. No one can say why he did it. (Not: No one can to say…)
2. All of them (except dare and need) form the negative and the interrogative form without the auxiliary verb.
E. g. You should not blame other people for your own mistakes. (Not: You do not should blame…)
3. All the modal verbs have two negative forms – a full one and a contracted one:
Should not – shouldn’t
May not – mayn’t
Must not – mustn’t
Need not – needn’t
Dare not – daren’t

Note the peculiar contracted form of some modal verbs:
Cannot – can’t [ka:nt]
Shall not – shan’t [∫a:nt]
Will not – won’t [wount]



Modal verbs