ter a certeza de que

be sure that; be certain that

→ ter
phrase Rare #22,495
be sure that; be certain that Commonly used in European Portuguese; in Brazilian Portuguese, “ter certeza de que” is more common. It is usually followed by the indicative when expressing certainty, though the subjunctive may occur in contexts involving doubt or uncertainty.
PO: É importante ter a certeza de que não está pegando o ônibus errado.
EN: It is important to make sure that you are not taking the wrong bus.

Vou procurar ter a certeza de que o Tom escreverá ao senhor.

I’ll make sure Tom writes to you.

Eu fiz o máximo possível para ter a certeza de que isso não tinha acontecido.

I did everything I could to make sure that hadn't happened.

Procurarei ter a certeza de que o Tom vai escrever à senhora.

I’ll make sure Tom writes to you.

Quero apenas ter a certeza de que estás preparada.

I just want to make sure you're ready.

Procure ter a certeza de que Tom virá.

Make sure you know Tom will come.