I must
Debo
You must
Debes
She must
Debe
We must
Debemos
They must
Deben
I had to (imperfect)
Debía
You had to (imperfect)
Debías
He had to (imperfect)
Debía
We had to (imperfect)
Debíamos
They had to (imperfect)
Debían
I had to (pretérito)
Debi
Tu had to (pretérito)
Debiste
She had to (pretérito)
Debió
We had to (pretérito)
Debimos
They had to (pretérito)
Debieron
I must (subjunctive)
Deba
You must (subjunctive)
Debas
He must (subjunctive)
Deba
We must (subjunctive)
Debamos
They must (subjunctive)
Deban
I should
Debería
You should
Deberías
He should
Debería
We should
deberíamos