I'm new in the field of teaching I came across the use of should have and shouldn't have (task 1 page 45) 2nd year classes. I have no idea how am I going to explain the use of these two to apologize and criticize because it's a bit ambiguous, especially having some pupils who really want to learn english and who question a lot. Would you please give me some instructions on how to teach the use of "should have and shouldn't have"? I'm so hopeless please help me.