W RD RDER: To show we are sure about something that happened in the past He must have felt happy when he graduated To show we are certain about something that did NOT happen in the past He can’t have been at the party last night He flew to Paris two days ago To show we had the ability to something in the past but did NOT it Joan and Larry could have come with us but they decided not to To show we are guessing about something that happened in the past I didn’t see Bob yesterday He may/might /could have been ill To say that He should have been more careful! somebody didn’t something he/she was supposed to or did something that he/she wasn’t To show willingness to something that Why didn’t wasn’t done you ask me? I would have helped you