Lin spent all her money on music downloads. Now she doesn't have money to go out. What shouldn't she have done?
She shouldn't have spent all her money.
Kris copied during his test. Now he's in trouble at school. What shouldn't he have done?
He shouldn't have copied during his test.
Last Tuesday was Alexis's uncle's birthday. She didn't send him a card. What should she have done?
She should have sent him a birthday card.