We use past possibility to talk about things which have possibly happened in the past to cause the situation we are in.
For example, John is late to work,he hasn’t arrived yet. Nobody knows what has happened to him, so we start to ask about the possible things which have made him late.
There are many possible reasons why John is late:
He has got stuck in traffic
He has got lost
He has forgotten
Some of these possibilities could be very likely, some could be quite likely (50%), some could be unlikely.
To discuss how possible it is that these events have happened we use the modal verbs must have, should have, may have, might have, can’t have.
Click on the image below to see which phrasal verb we use for each situation, then why not try one of our downloadable worksheets: