to make sure that
Tu es venu t'assurer que j'étais bien mort !
You came to make sure I was really dead!
— Shower (1999)
Je peux t'assurer que tu as tort.
I can assure you that you're wrong.
Tu ferais bien de t'assurer que c'est vrai.
You’d better make sure it’s true.
Tu dois t'assurer que je continue à boire cette potion.
You have to make sure I keep drinking this potion.
— Harry Potter et le Prince de sang-mêlé (2009)
Je te prie de t'assurer que ta ceinture est attachée.
Please make sure your seat belt is fastened.