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Modal verb ‘can’ (forms & substitute)

Forms and substitute of ‘can’ in all tenses

(Overview of the modal verb ‘can’ in all tenses)

Contents

  1. General information
  2. Verb forms in the tenses
    1. Present tense forms
    2. Past tense forms
    3. Future tense forms
  3. Infinitives and imperatives

Particularities of the verb forms

  1. ‘can’ is a modal verb and can be only an auxiliary verb.
  2. It has proper forms only in the present and past. For the other tenses, the substitute form ‘to be able to’ has to be used, which follows the conjugation scheme of ‘to be’. However, the meaning of ‘can’ and ‘be able to’ differs slightly.

Forms of the modal verb ‘can’ in all tenses

Here, the verb ‘can’, including its substitute form, exemplifies the possibility of using modal verbs in all tenses. However, modal auxiliaries like ‘can’ never form the continuous or progressive aspect. The tables also highlight the particular forms that differ from the repeating ones. For clarification, the grammatical persons are presented as follows:

Number Person
Singular 1 I
2 you
3 he, she, it
Plural 1 we
2 you
3 they

Forms in the present

Tense Person and subject Simple Substitute form
Present 1 I
2 you
3 he, she, it
1 we
2 you
3 they		 can am able to
are able to
is able to
are able to
are able to
are able to
Present perfect 1 I
2 you
3 he, she, it
1 we
2 you
3 they		 only substitute form → have been able to
have been able to
has been able to
have been able to
have been able to
have been able to
  • Information: Negations are formed by directly appending ‘not’ to ‘can’ (→ cannot).

Forms in the past

Tense Person and subject Simple Substitute form
Past 1 I
2 you
3 he, she, it
1 we
2 you
3 they		 could was able to
were able to
was able to
were able to
were able to
were able to
Past perfect 1 I
2 you
3 he, she, it
1 we
2 you
3 they		 only substitute form → had been able to
  • Information: Here, negations are also formed with ‘not’. However, it is placed after the word ‘could’ instead of being appended directly to it (→ could not), as is the case with its abbreviated form (→ couldn’t). Note the difference in meaning between ‘can’ and ‘could’.

Forms in the future

Tense Person and subject Simple Substitute form
Future (will) 1 I
2 you
3 he, she, it
1 we
2 you
3 they		 only substitute form → will be able to
Future (going to) 1 I
2 you
3 he, she, it
1 we
2 you
3 they		 only substitute form → am going to be able to
are going to be able to
is going to be able to
are going to be able to
are going to be able to
are going to be able to
Future perfect 1 I
2 you
3 he, she, it
1 we
2 you
3 they		 only substitute form → will have been able to

Infinitives and imperatives of ‘can’

The imperative expresses commands and generally exists only in the 2nd person singular and plural. As ‘can’ is limited in its forms, it does not have an imperative either:

Person and subject Imperative (affirmative) Imperative (negated)
2 you
2 you		 –
–		 –
–

The infinitive is the base form and, like the participles, appears in different aspects. Here, the auxiliary ‘can’ is similarly restricted and requires its substitute form:

Verb form (aspect) Infinitive Present participle Past participle
Simple can being able to been able to
Progressive – – –
Perfect to have been able to having been able to
(perfect participle)		 –
Perfect progressive – – –
  • Information: Although there is no proper progressive form of ‘can’, its past form may be combined with a main (lexical) verb in the continuous form (the progressive aspect of modal verbs: could be doing).
  • Here, too, ‘can’ cannot directly be used in the perfect tense but only its substitute form. A combination (mostly of ‘could’) with another verb in the perfect is possible, but the meaning may change (see modal verbs in the perfect: can’t/could have been).