She must have left: modal perfects
Judge what probably happened, and criticise or regret past actions
What you'll be able to do
Work out what probably happened from the evidence, and say what someone should or shouldn't have done, at work, in stories, or when something goes wrong.
Deduction about the past
| Form | Meaning | Example |
|---|---|---|
| must have + participle | I'm almost sure it happened | The lights are off. They must have gone out. |
| can't have / couldn't have | I'm almost sure it didn't happen | She can't have seen us; she didn't wave. |
| might / may / could have | perhaps it happened | He might have missed the bus. |
Criticism and regret
| Form | Meaning | Example |
|---|---|---|
| should have | it was the right thing, but it didn't happen | You should have told me. |
| shouldn't have | it happened, but it was wrong | I shouldn't have eaten so much. |
| needn't have / didn't need to | it wasn't necessary | You needn't have brought a gift. |
- You should have called me.you didn't, and that was wrong
- She must have forgotten.I'm almost sure
- They might have taken the wrong road.perhaps
- He can't have finished already.I'm sure he hasn't
Common mistakes
She must went home.→ She must have gone home.You should told me.→ You should have told me.He mustn't have seen us.For a negative deduction: He can't have seen us.- In speech, should have sounds like "should've", never "should of".
Practice
- Her car isn't here. She _____ home already.Options: must have gone · must go · should have gone
Show the answer
must have gone — Almost sure from the evidence: must have + participle.
- He _____ the message; he hasn't been online all day.Options: can't have read · mustn't have read · shouldn't have read
Show the answer
can't have read — Sure it didn't happen: can't have.
- You _____ me you were ill! I would have helped.Options: should have told · must have told · might have told
Show the answer
should have told — Criticism of something that didn't happen: should have.
- I'm not sure why Tom is late. He _____ the wrong bus.Options: might have taken · must take · should have taken
Show the answer
might have taken — Perhaps: might have + participle.
- I feel sick. I _____ (not / eat) so much cake.
Show the answer
should not have eaten — Regret about something that happened: shouldn't have.
In the app, this lesson is taught one idea at a time with the examples read aloud, then practised with questions you answer by choosing or typing. It comes back for review on later days, until you can use it without help.
More on this topic: English modal verbs: must, have to, should and more