I couldn't / I wouldn't know how to
Je ne saurais être plus claire.
I couldn't be clearer.
Je ne saurais pas te dire à quel point je t'aime.
I can’t tell you how much I love you.
Je ne saurais vous le recommander, Monseigneur.
I cannot recommend it to you, Your Grace.
— Dune : Première partie (2021)
I can't praise her enough.