What does "should have p.p" mean? and is it okay to say just "should" here?

Rebecca

"Should have" is used in this case to express that something did not happen, but one wishes that it did, and so it is used to express a past mistake or failure. "Should have" is always used with a past tense verb. It would not be correct to use "should" in this case because "should" is used to express an expectation or give an opinion to someone. Additionally, "should" is usually attached to the simple or base form of the verb while the "have" in "should have" is attached to a past tense or completed verb to turn it into the perfect form of the verb to indicate that the action has been completed. Here's another example: Ex: You should eat something before you go to school. Ex: You should have eaten something before you went to school.