fgjyhjyyjGrammatical behavior of modal verbsGrammatically, modal verbs behave in a different way from ordinary verbs.They have no -s in the third person singular (he, she, it).She mights go to class. Most modal verbs, except for ought, are followed by the verb without to.Gallaudet should to build a new computer center. Modal verbs have no infinitive or -ing form.My teacher can signing well. They make questions and negative forms without using do/did:May I see that? / You mustn't shout.Note that some modal verbs appear to have past tense forms (could, should, might), but these are not usually used with a past meaning. One exception is could which, when talking about ability, is used as a past form of can:I could run a long way when I was younger.Most modal verbs can be used in some of their meanings with a perfect infinitive to talk about the past:I may have seen him yesterday. You should have told me last week.