To speculate about something in the past we use may/might (not) + have + past participle. We can replace may/might with could in positive sentences, but not with can.Įxample: Max’s father may/might/could retire soon, he is almost 60. We use may/might when we think something is perhaps true, but we are not 100% sure.Įxample: Max may/might not want to work in the garage forever.