MODAL PERFECTS: Could have / Should have / Would have / Must have / May have / Might have. Advanced English Grammar

Modal Perfects: Explained in Simple English

Modal perfects are phrases we use to talk about past possibilities, regrets, guesses, or things that didn’t happen but could have happened. They are formed using a modal verb (could, would, should, must, may, might) + have + a past participle (e.g., eaten, gone, seen). Let’s look at each one with examples.

1. Would Have

Use this when something was 100% certain to happen, but it didn’t because of some reason.
Example:
- He would have helped you if he had known about your problem. (He was willing to help, but he didn’t know about the problem.)
- I would have gone to the party, but I was sick. (I wanted to go, but I couldn’t.)

2. Could Have

Use this when there was a possibility (around 70%) for something to happen in the past, but we’re not sure, or it didn’t happen.
Example (Possibility):
- They could have seen the movie last night. (It’s possible they saw it, but we’re not sure.)
- She could have left her phone at home. (We think it’s likely, but we don’t know for sure.)
Example (Option):
- You could have taken a taxi instead of walking. (There was a choice or option, but you didn’t do it.)

3. May Have / Might Have

Use these when there is a smaller possibility (around 30%) that something happened in the past.
Example:
- He may have forgotten the meeting. (It’s possible, but not very likely.)
- They might have missed the train. (There’s a chance this happened, but we don’t know for sure.)

4. Should Have

Use this to talk about past actions that were a good idea, but didn’t happen.
Regret (for yourself):
- I should have studied harder for the test. (I didn’t study enough, and now I regret it.)
- We should have left earlier to avoid traffic. (We didn’t leave early, and now we’re stuck.)
Blame (for others):
- You should have told me you were sick. (You didn’t tell me, and I’m upset about it.)
- She should have called her parents. (She didn’t call, and it was her responsibility.)

5. Must Have

Use this to make a strong guess about what happened in the past based on evidence.
Example:
- He must have been tired after running a marathon. (We are almost sure because running is exhausting.)
- They must have forgotten about the meeting. (We strongly believe this because they didn’t show up.)

Quick Comparison

Modal Perfect	Use	Example
Would Have	100% certainty (didn’t happen)	I would have gone, but I was busy.
Could Have	Possibility or option	She could have stayed longer.
May/Might Have	Small possibility	He might have left his keys at home.
Should Have	Regret or blame	You should have checked your email.
Must Have	Strong guess	They must have been late because of traffic.

Extra activities!

Practice Examples

1. You see an empty coffee cup on your coworker’s desk, but they aren’t around.
They _____ drunk the coffee before leaving.
(Must have / Should have / Could have)

2. You forgot to set your alarm last night and woke up late this morning.
You _____ set your alarm.
(Would have / Should have / Must have)

3. The ground is wet, and the sky is cloudy.
It _____ rained last night.
(Could have / Would have / Must have)

4. Your friend promised to meet you at 5 PM, but they didn’t show up until 6 PM. Later, they say they got stuck in traffic.
They _____ left earlier to avoid being late.
(Should have / Must have / Might have)

5. There’s a half-eaten sandwich on the counter, and your dog is hiding under the table.
The dog _____ eaten the sandwich.
(May have / Must have / Would have)

6. Your friend tells you they saw Mark buying flowers.
Mark _____ bought the flowers for his girlfriend.
(Could have / Must have / Might have)

7. You see Sarah walking into the office with a big smile on her face, and she mentions a meeting with her boss.
She _____ received good news during the meeting.
(Might have / Must have / Should have)

8. You hear that Olivia got a bad grade on her exam because she didn’t study enough.
She _____ spent more time studying.
(Would have / Should have / May have)

9. You arrive at a restaurant, and there’s a “Closed” sign on the door.
They _____ closed early today because of a staff shortage.
(Could have / Must have / Might have)

10. Your friends were planning to watch a movie, but you heard they changed their minds at the last minute.
They _____ gone to a different restaurant instead.
(Would have / Could have / Must have)

Answers

Must have – They must have drunk the coffee before leaving. (Strong guess based on evidence.)
Should have – You should have set your alarm. (Regret for a missed action.)
Could have – It could have rained last night. (Possibility.)
Should have – They should have left earlier to avoid being late. (Blame.)
Must have – The dog must have eaten the sandwich. (Strong guess based on evidence.)
Might have – Mark might have bought the flowers for his girlfriend. (Small possibility.)
Must have – She must have received good news during the meeting. (Strong guess based on her reaction.)
Should have – She should have spent more time studying. (Regret.)
Might have – They might have closed early today because of a staff shortage. (Small possibility.)
Could have – They could have gone to a different restaurant instead. (Possible option.)

Quiz: Modal Perfects

Choose the correct modal perfect for each situation. The answers are at the bottom.

1.

There’s a loud noise coming from outside your window, and you see a group of kids playing near your car.
One of them _____ hit the car with a ball.
Choices:

Could have
Must have
Might have

2.

You saw John leave work at 6 PM, but the meeting started at 6:30 PM, and his car isn’t in the parking lot.
He _____ gone home before the meeting.
Choices:

Could have
Must have
Might have

3.

There’s a half-eaten pizza on the counter, and your dog is looking guilty.
The dog _____ eaten the pizza.
Choices:

May have
Must have
Should have

4.

Your friend didn’t take an umbrella because the sky looked clear, but now they are completely drenched.
They _____ brought an umbrella if they had checked the weather app.
Choices:

Would have
Could have
Must have

5.

The party was amazing last night. Emma said she danced until 3 AM and then went home.
She _____ been exhausted this morning.
Choices:

Could have
Must have
Might have

6.

The cake is missing from the fridge, and there are a few guests who look suspicious.
Any one of them _____ taken the cake.
Choices:

May have
Could have
Must have

7.

Sarah didn’t bring her umbrella even though it was raining this morning, and now her clothes are soaked.
She _____ checked the weather before leaving the house.
Choices:

Should have
Would have
Must have

8.

You invited Emily to the movie night, but she didn’t come. Later, she said she didn’t check her messages.
She _____ come if she had read your message.
Choices:

Would have
Could have
Must have

9.

Mark said he was stuck in traffic for two hours. However, you checked the news, and there were no traffic reports that day.
He _____ been lying.
Choices:

Should have
Must have
Could have

10.

It’s already 10 PM, and no one has heard from Daniel. He always comes home by 8 PM.
He _____ stayed late at work.
Choices:

May have
Must have
Should have

11.

You were trying to solve a tough math problem, but you realize later that you skipped a simpler method.
You _____ solved it faster if you had thought of that method earlier.
Choices:

Would have
Could have
Should have

12.

Anna regrets not studying for her test. She got a very low score.
She _____ studied harder.
Choices:

Would have
Should have
Might have

13.

There’s a giant stain on your roommate’s shirt, and it smells like coffee.
He _____ spilled his coffee this morning.
Choices:

May have
Must have
Should have

14.

The car isn’t starting, and there’s a strong smell of gas.
You think: “The engine _____ been flooded with fuel.”
Choices:

May have
Must have
Could have

15.

If the store had stayed open another 10 minutes, you _____ bought the groceries.
Choices:

Would have
Could have
Must have

16.

You find an empty water bottle in the trash can, but no one is home.
Someone _____ drunk the water.
Choices:

May have
Must have
Could have

17.

You hear someone knocking on the door late at night, but when you open it, no one is there.
It _____ been the wind.
Choices:

Could have
Must have
Might have

18.

Your friend promised to join you for dinner but didn’t show up. Later, you find out she had a flat tire on the way.
She _____ called to let you know.
Choices:

Could have
Should have
Must have

19.

Olivia looks upset, and you just remembered that you forgot her birthday yesterday.
You _____ wished her a happy birthday.
Choices:

Must have
Could have
Should have

20.

You are waiting for your friend at the park, and she’s 30 minutes late. She mentioned earlier that her bus was delayed.
She _____ missed the bus.
Choices:

Could have
Should have
Must have

Answers:

1. One of them could have hit the car with a ball. (70% possibility)
2. He must have gone home before the meeting. (Strong guess)
3. The dog must have eaten the pizza. (Strong guess)
4. They could have brought an umbrella if they had checked the weather app. (Option)
5. She must have been exhausted this morning. (Strong guess)
6. Any one of them could have taken the cake. (Option)
7. She should have checked the weather before leaving the house. (Blame)
8. She could have come if she had read your message. (Option)
9. He must have been lying. (Strong guess)
10. He may have stayed late at work. (Possibility)
11. You could have solved it faster if you had thought of that method earlier. (Option)
12. She should have studied harder. (Regret)
13. He must have spilled his coffee this morning. (Strong guess)
14. The engine must have been flooded with fuel. (Strong guess)
15. You could have bought the groceries. (Option)
16. Someone may have drunk the water. (Possibility)
17. It might have been the wind. (Possibility)
18. She should have called to let you know. (Blame)
19. You should have wished her a happy birthday. (Blame)
20. She could have missed the bus. (70% possibility)