Part 1May have . . .Might have . . .Could have . . .

*used to give possible explanations for past events

Used to give possible reasons why something happened or didn’t happen in

the past.

Why was Tomas late to class on Monday?

I’m not sure.He may have missed the bus.

He might have woken up late.

He could have forgotten to set his alarm clock.

Why didn’t John come out to lunch with us yesterday?

I’m not sure.He may have been busy at work.

He might have had too much work to do.

He could have gone to a meeting.

What do you think your husband got you for your

anniversary?I don’t know.He may have bought me a new kitchen appliance.

He might have gotten me some jewelry.

He could have picked out some perfume for me.

I wonder why Susan seemed so sad yesterday.

I’m not sure.She may have broken up with her boyfriend.

•She might have gotten low scores.

•She might have felt sick.

I wonder why the teacher wasn’t in class on Friday.

•He may have been sick.

•He might have gone rock climbing.

•He might have decided to take a relaxing day off.

Part 2Must have . . . *stronger than -may have-might have-could have

Meaning / Use:•Must have = similar to the use of may/might/could have…•Must have shows more certainty than may/might/could have…

•Use must have + past participle to show a strong probability

Comparison: may/might/could have… versus must have…

John wasn’t in class today. I wonder why . . .

He could have been sick. OR

He may not have felt well.

He must have been sick.OR

He must not have felt well.

Janet looks really tired today. It’s strange to see her this way because she is usually very

energetic.

She mustn’t have gotten very much sleep last night.

Did you see how well Sam played during the soccer game? I was really surprised that he scored 4 goals because he usually doesn’t play that well.

He must have practiced a lot before the game.OR

He must have been practicing a lot recently.(progressive form)

Structure:How to make this

grammarMayMightCouldMust

For the NEGATIVE:

Couldn’t/can´tMustn´tMay not/Might not

Negative Examples:

Richard’s wife bought a new table 2 weeks ago, but Richard still hasn’t assembled it.I wonder why?

He must NOT have understood the instructions.

She might have left already.

They could have misunderstood the instructions.

Susan might have quit her job.

She must have gone home early today.

Cynthia might have tried to call me when I out walking my dog.

Now it’s YOUR turn!What do you think? What are some possible reasons why these things happened? Write them on a piece of paper and show your writing to your teacher.

1. I wonder why Janet didn’t come to school today?

2. I wonder why Lisa and her husband decided to move to Temecula.

3. I wonder what my mother got me for my birthday.