Summary Chart of Past Modals






Could have

(+ past participle)











I could’ve ordered dessert, but I was already full.


I couldn’t have married  her because neither of us wanted to move to another country.


How could you have thought I would accept such a foolish excuse?



May/Might have

(+ past participle)



possibility (may or might)







We didn’t tell her the truth, because we were afraid or hurting her feelings.  However, she may have suspected that we weren’t telling her the truth.


He might have tried to be more cooperative.  In that case, his coworkers would have been more likely to help him.



Should have/Ought to have

(+ past participle)






regret or judgment about past action



She ought to have called by now, since it’s 8:15 and she said she’d call by 7:30.


I know I should have told her the truth.  (But I didn’t and I regret it.)


Must have

(+ past participle)




He must have taken my grammar book home.  I accidentally picked up his book, and I guess he took mine. 



Would have

(+ past participle)





Unfulfilled wish


I would rather have gone to the park, but she wanted to see a movie.


I would have liked a cookie, but there weren’t any in the house. 



Past modals are often used to express unfulfilled or unrealized actions or events.  The past modals can also be used in progressive and passive verb constructions.


Modal + progressive: You should have been keeping all of your work in a folder. 


Modal + passive:  Your work should have been kept in a folder.