modals: possibility, uncertainty,
certainty (past)
Usecould, may, might +have+past participie- to describe things that possibly happened in the past.
I don 't know where my bag isoI suppose someone else might have taken /could have taken it by mistake.
scientists now believe that ice may have shaped the surfaceofthe planet Mars.
Usecould, might +have+past participie- to make a contrast between what was possible in the past and what actually happened.
That wasastupid thing to do' You might have hurt someone.
It was lucky you didn't light the gas. It could have exploded. - to criticize someone's actions.
You might have told methe bus left at 3.001 I missed iti
e
Usecan't have+ past participle- when we are certain something was not true.
Istiii haven't heard from Peter. He can't have got my message.
Usemust have +past participle- when we are certain something was true.
Congratulations on your exam resu/ts. You must have been really pleased when you heard the news.
After the volcanic eruption on the Greek islandofSantorin i in about J650 Be there must have been
ahuge tsunami.
Usecould, mayand might and could have, may have, might have- in conditional sentences, when the results are not certain.
!f you heat the solution too quickly, it may/might /could explode.
!fwefound water on Mars,wecould use it to make rocket fuel.
!f the dinosaurs had survived, they might have stopped mammals developing.
!f you hadn't reminded meabout the party, I might have forgotten ali about it.