Use past modal verbs

THE 9TH OF DECEMBER
MNEMONICS
You will learn:
about the phenomenon "bizarreness effect".
You will be able to:
use past modal verbs.

Should have, could have, and would have can be called “modals of lost opportunity” because they describe unreal situations we can’t change.
If you arrive late to a lecture, you can say:
“I should have taken a taxi.”
If you regret you forgot something, you can say:
“I shouldn’t have forgotten about it. I’m sorry.”
Look at these examples to see how modals are used in the past:
1. Did you have a lecture on mnemonics? That must have been amazing!
2. We don't know for sure that Maksat took the book. It might have been Marat.
3. How did they fail that exam? They can't have studied very much.

We use would have to imagine a result (if something had been different in the past):
If you arrive late at the airport and miss your flight, you can say:
“If we had arrived earlier, we would have caught our flight.”
If you forget your umbrella, and it starts to rain, you can say:
“If I had brought my umbrella, I wouldn’t have got wet in the rain.”
We use could have to talk about possibilities if something had been different in the past.
For example, someone who forgot about his passport:
“If I had found my passport, I could have gone to Australia.”
When talking about a sportsman who didn’t win a competition, you can say:
“He could have won the gold medal if he hadn’t forgotten about his weaknesses.”