Utilisez l'auxiliaire modal qui convient le mieux (+ «present perfect») pour former une nouvelle phrase en réemployant certains des éléments donnés.

Modaux à utiliser : may / should / can't / needn't / could / must

Par exemple : Why didn't he phone his mum? It was her birthday. He should have phoned his mum on her birthday.

Why didn't you tell her yesterday? It was important.
You have her yesterday.
It's very likely that he was embarrassed.
He have embarrassed.
She didn't forget to go to her interview! It's impossible!
She have to go to her interview!
It's quite possible that it was done without her knowledge.
It have without her knowledge.
I'm not certain but perhaps the letter arrived on May 23rd.
It have on May 23rd.
Why did you do it? It wasn't necessary.
You have it.