A: Clothes are all over the floor, and he looks annoyed. B: (clean it yesterday) [regret]
He should have cleaned it yesterday.
A: He is running, but the bus has already left. B: (leave home earlier) [regret]
He should have left home earlier.
A: He is standing next to his car, looking worried (ran out of gas) - question
Could it have run out of gas?
A: No one is around at her birthday party, and she is looking disappointed (not send invitations) - question
Could she not have sent the invitations?
A: He is sitting on the field looking frustrated after missing a penalty. B: (practice more) [regret]
He should have practiced more.
A: She is holding her broken phone and crying. What happened? B: (drop it on the floor) [possibility]
She might have dropped it on the floor.
A: She is holding her exam with a failing grade and lamenting. B: (study harder) [regret]
She should have studied harder.
A: His ice cream is on the ground, and he is sad (drop it) - question
Could he have dropped it?
A: They are shouting at the waiter and looking angry in a restaurant. B: (forget their order) [possibility]
The waiter might have forgotten their order.
A: He is walking under the sun holding an umbrella (think it would rain) - question
Could he have thought it would rain?
A: He is sneaking into class as the teacher looks at him (wake up earlier) - question
Should he have woken up earlier?
A: He is sleeping during the lesson because he looks exhausted. What happened? B: (go to bed late) [possibility]
He might have gone to bed earlier, he could've gone to bed late