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Murder Mystery Scene 1 - Language Focus

Rob and Stephen look at how ‘must’, ‘could’ and ‘perhaps’ can be used to speak about certainty and possibility.

Watch the video. Then go to the Tasks and do the activities.


Language level

Intermediate: B1


Hi guys ,
In Task (3) number (6) they said (could have just left ) , is there any difference if i say ( might be left ) both are predictions .
Many Thanks .

Hi Fouka,

These are examples of modal verbs used for deductions about the past. There are five alternatives:

must have + past participle (a very strong, almost certain decuction)

may/might/could have + past participle (a less strong, possible deduction)

can't have + past participle (a very strong, almost certain negative deduction)

As you can see, we can use 'could', 'may' and 'might' interchangeably, so the answer to your question is that both 'could' and 'might' are possible.

Best wishes,



The LearnEnglish Team