Past substitute: “You had to call your mother.”.This past tense form with ‘-ed’ does not exist for this verb and is, therefore, wrong.This form then demonstrates ability, obligation, etc. The usual method of expressing the past is to conjugate the substitute form in the past tense, which every modal verb has. Compare the two sections: Substitute forms of modal verbs for the past The combination of ‘ have’ and a past participle (perfect infinitive)īoth have different meanings.To still refer to and talk about the past, there are two possibilities: An exception is ‘ could’ (the past form of ‘can’). In principle, you cannot use modal verbs (‘ may, can, will, must, would,’ etc.) in past tenses because they lack the necessary past tense forms.
