Modals of deduction and speculation

Nobody knows exactly why he died. But we think it ______ have been an accident.

• can have

• may have

• might have

Answer explanation

➪ We can use might/may have + past participle to talk about something that perhaps happened or was true.

➪ We can use can't but not can as a modal verb of deduction.

➪ It might have been an accident= Maybe it was an accident.

I _____ revised more for the exam. I was lazy, and now I'll fail!

• might have

• should have

• could have

Answer explanation

Correct answers: should have / could have

➪ We can use could have + past participle to say that something was possible in the past, or you had the ability to do something in the past, but that you didn't do it.

➪ We can use should have + past participle to talk about a situation that we expected to happen in the past, but it didn't. We often use this form to express criticism.

Sarah looked very happy. She _____ passed her driving test.

• must have

• should have

• can't have

Answer explanation

Correct answer: must have

➪ We can use must have + past participle to say that we are quite sure that something was true or happened in the past.

➪ She must have passed her diriving test = I'm sure she passed.

I didn't know you were going to Phil's party yesterday. You _______ told me!

• can't have

• should have

• must have

Answer explanation

Correct answer: should have

➪ We can use should have + past participle to talk about a situation that we expected to happen in the past, but it didn’t.

➪ We often use this form to express criticism

I can't believe Jim hasn't arrived yet. He ______ taken the wrong train.

• can have

• should have

• must have

Answer explanation

Correct answer: must have

➪ We can use must have + past participle to say that we are quite sure that something was true or happened in the past.

➪ She must have taken the wrong train= I’m sure she took the wrong train.

I can't believe Jim hasn't arrived yet. He ____ taken the correct train.

• shouldn't have

• mustn't have

• can't have

Answer explanation

Correct answer: can't have

➪ We can use can’t/couldn’t have + past participle to say that we are quite sure that something did NOT happen or was NOT true in the past.

➪ He can't have taken the correct train.= I'm quite sure he didn't take the correct train.

You _____ been ill yesterday. Jessie saw you at the bowling alley.

• mustn't have

• may not have

• couldn't have

Answer explanation

Correct answer: couldn't have

➪ We can use can’t/couldn’t have + past participle to say that we are quite sure that something did NOT happen or was NOT true in the past.

➪ You couldn't have been ill.= I'm quite sure you weren't ill.

➪ We can use must but not mustn't as a modal verb of deduction.

I don't know where they went but they ____ gone to Paris or Marseille.

• must have

• could have

• can have

Answer explanation

Correct answer: could have

➪ We can use could/might/may have + past participle to talk about something that perhaps happened or was true.

➪ They could have gone to Paris or Marseille.= Perhaps they went Paris or Marseille.

➪ We can use can't but not can as a modal verb of deduction.

You ____ paid more attention. Now we are lost.

• ought to have

• can't have

• must have

Answer explanation

Correct answer: ought to have

➪ We can use should/ought to have + past participle to talk about a situation that we expected to happen in the past, but it didn’t.

➪ We often use this form to express criticism.

The window was broken, so the thieves _____ got in through that window.

• may have

• must have

• should have

Answer explanation

Correct answer: must have

➪ We can use must have + past participle to say that we are quite sure that something was true or happened in the past.

➪ The thieves must have got in through that window.= I'm quite sure the thieves got in through that window.