ESL 099Speculations and Conclusions About the Past

Speculations and Conclusions About the PastMay have Might haveCould have + Past participleMust haveHad to have

Speculations or Possibilities About a Past SituationMay have, might have, could have + past

participleTo express speculations or possibilitiesUsually based on facts that we don’t have

Tom’s absent today. Where is he? I have no idea. He may be at work.

• He could have an appointment.• He may be at work.

ConclusionsMust have and had to have + past participleUse when you are almost certain about your

conclusionsHow was the weather?

Well, Tom’s hair and shirt were wet when he came in. It must have been (had to have been) raining.

My husband looked tired after work. He must have had (had to have had) a hard day.

Negative StatementsDo not use HAD TO HAVE in negative

statements to draw conclusions.The must not have been very easy to move.

NOT They didn’t have to have been easy to move.

QuestionsUse COULD HAVE in questions about

possibility. Do not use MAY HAVE/MIGHT HAVE.

Could the students have cheated?

Short AnswersUse BEEN in short answers to questions that

include a form of BE.Could Eric HAVE BEEN wrong?

Yes, he could have been.

Use only the MODAL + HAVE in short answers to questions with other verbs. Did he cheat on the test? Yes, he MUST HAVE.