Grammar: Perfect modals

Hello,

here I leave you an explanation about perfect modals, I have already explained about them but just in case, take a look:

Some practice exercises:

• http://web2.uvcs.uvic.ca/elc/studyzone/410/grammar/410-modals-of-possibility-and-probability-for-past-situations1.htm
• http://www.autoenglish.org/modalverbs/pastmodalsdeduction.htm
• http://www.english-at-home.com/lessons/grammar-exercise-past-modals/
• http://www.esl-lounge.com/student/grammar/4g66-past-modals-exercise.php