MODAL VERBS

REGRETS:

Pronoun + should/ shouldn't + have + past participle:

I should have organised my workplace this morning, because now I have too much work and I don't have time to do so.

Pronoun + ought/ Ought not to+ have+ past participle

I ought not have to spend so much time whatching TV. Now it's too late to start my homework.

LACK OF OBLIGATION:

Pron needn't + have + past participle

I needn't have planned the class, because we didn't have class last week.