you have to know
Il y a quelque chose que tu dois savoir.
There is something you need to know.
Tu dois savoir distinguer le bien du mal.
You must know how to distinguish good from evil.
Tu dois savoir que le fils de Sompat, Dan, a disparu il y a un an.
You should know that Sompat’s son, Dan, disappeared a year ago.
— Detective Chinatown (2015)
Il y a deux choses que tu dois savoir.
There are two things you need to know.
Il y a des choses que tu dois savoir.
There are things you need to know.
Tu dois savoir ce que tu fais.
You have to know what you're doing.
Tu sais tout ce que tu dois savoir.
You know everything you need to know.