1. Using perfect modals

Generally we use the perfect modals for:

1. Events that didn’t happen in the past
2. Events that couldn’t have happened.

2. Should have / shouldn’t have

Uses:

  1. Regret
  2. Strong judgement against others
RegretStrong judgement
I failed my test; I should have studied harder.I’ve been worried about you. You should have called!
I feel sick: I shouldn’t have eaten all those hamburgers.They’re going to get divorced because of you. You shouldn’t have kissed her!

3. Could have / couldn’t have

Uses:

  1. Possibilities / Impossibilities
  2. Mild judgement of another
  3. Disbelief
PossibilitiesMild judgementDisbelief
Thank god you were there: they could have died.Why did you buy that? You could have bought the blue one.No way! You couldn’t have paid that much.
I could have gone if I hadn’t had to work.You could have called me! I wanted to go to the party too.What? I don’t believe you. China couldn’t have beaten Brazil 5-0.
He couldn’t have killed your dog: he was on holiday.You could have helped me instead of watching football on the sofa.Amy couldn’t have done that. She can’t even swim!

4. Would have / wouldn’t have

Uses

  1. Willingness / unwillingness to do something
  2. Showing how different people would act
WillingnessHow different people would act
I would have called, but I had no credit left.You bought the red car? I would have bought the blue.
I wouldn’t have gone, but it was his birthday.You know, if he had been here he would have punched you.

5. Must have

Uses

  1. Logical Conclusion
Logical conclusion
The lights are off; they must have all gone to bed.
The house is soaked. The dishwasher must have leaked.

6. Exercises

Choose the right ‘modal + have’
(i) There was a cake. Peter was home all day. Now there is no cake.
(ii) She was waiting for his call. He didn’t call her. Now she is upset.
(iii) He called his friend about his problem. I think that was a bad idea: in my opinion calling a doctor was a better idea