Should have, could have, and would have. These are often called models of lost opportunity because they describe situations when we are imagining that the past was different. First, let's review the general rule for should, could, and would. Use should for recommendation. If you want to lose weight, you should eat healthy food. Use could for possibilities. I have the day off tomorrow. Great! We could spend the day at the beach, or we could go shopping. Use would for imagining results. If I were rich, I would buy a boat. This general rule of should for recommendation, could for possibilities, and would for imagining results, applies to should have, could have, and would have. Use should have when a different action was recommended in the past. If you arrive late to class, you can say, I should have left my house earlier. If you regret an argument, you can say to the other person, I shouldn't have yelled at you yesterday. I'm sorry. If your son fails a test, you can tell him, you should have studied. You shouldn't have played video games all weekend. Use could have to introduce possibilities if something had been different in the past. For example, someone who didn't go to college could say, if I had gone to college, I could have gotten a better job. When talking about a gymnast who didn't win a competition, you can say, she could have won the gold medal if she hadn't fallen three times. Use would have to imagine a result if something had been different in the past. For example, if you arrive late at the airport and miss your flight, you can say, if we had arrived earlier, we would have caught our flight. If you forget your umbrella, and it starts to rain and you get wet, you can say, if I had brought my umbrella, I wouldn't have gotten wet in the rain. Again, you are imagining the result if the past had been different. Would have expresses more certainty than could have, which only introduces a possibility. For example, if I had worked harder, I could have gotten promoted. This means maybe you would get the promotion, but maybe not. It was only a possibility. I got a 68 on the test. If I had gotten two more points, I would have passed. With two more points, you definitely would have passed the test. It's certain. So, to review, use should have to recommend a different action in the past, could have to introduce possibilities if the past was different, and would have to imagine definite results if the past was different. In spoken English, most people say, should have, could have, and would have. Thanks for watching English Tips from Espresso English. If you liked this video, please share it.