using the past modals to show degrees of certainty 
by using the form of ( must have V3) to show that the action was almost certain . 
( could/might/ may have V3)  to s how that it is possible 
( couldn't have V3) to show that it is not possible

past-modals-for-degrees-of-certainty-activities-promoting-classroom-dynamics-group-form_52154.docx

Past modals for degrees of certainty

past-modals-for-degrees-of-certainty

Let's do English ESL general grammar practice. using the past modals to show degrees of certainty 
by using the form of ( must have V3) to show that the action…