Should have + past participle

Should have + past participle
1: Should have + past participle can mean something that would have been a good idea, but that you didn t do it. It s like giving advice about the past when you say it to someone else, or regretting what you did or didn t do when you re talking about yourself.
Shouldn t have + past participle means that something wasn t a good idea, but you did it anyway.
• I should have studied harder! (= I didn t study very hard and so I failed the exam. I m sorry about this now.)
• I should have gone to bed early (= I didn t go to bed early and now I m tired).
• I shouldn t have eaten so much cake! (= I did eat a lot of cake and now I don t feel good.)
• You should have called me when you arrived (= you didn t call me and I was worried. I wish that you had called me).
• John should have left early, then he wouldn t have missed the plane (= but he didn t leave early and so he did miss the plane).
2: We can also use should have + past participle to talk about something that, if everything is normal and okay, we think has already happened. But we re not certain that everything is fine, so we use should have and not the present perfect or past simple. It s often used with by now .
• His plane should have arrived by now (= if everything is fine, the plane has arrived).
• John should have finished work by now (= if everything is normal, John has finished work).
We can also use this to talk about something that would have happened if everything was fine, but hasn t happened.
• Lucy should have arrived by now, but she hasn t.