I would know
Ainsi, je saurais si on m'avait téléphoné pendant mon absence.
That way, I’d know if anyone had called while I was away.
— Assurance sur la mort (1944)
Sur la rivière, je pensais qu'en le voyant je saurais quoi faire.
On the river, I thought that seeing him would tell me what to do.
— Apocalypse Now (1979)
Ce n'est pas avec ce que tu m'as dit que je saurais me débrouiller.
I wouldn't know how to manage based on what you told me.
— The Umbrellas of Cherbourg (1964)
Je saurais que c'est lui quand il sera là.
I would know it was him when he was there.
— Demon Slayer : Kimetsu no Yaiba - Le film : Le train de l'Infini (2020)
Comment je saurais si vous pouvez me défendre ?
How will I know if you can defend me?