"One cannot know everything."
Translation:Нельзя всё знать.
Practically all the russian sites I go to tell me never to use 'не можно'; you use нельзя for both "impossible" and "not allowed to".
Моей сестре нельзя есть шоколад. = My sister can't eat chocolate (maybe she can't digest it). This refers to capability.
Здесь нельзя курить. = You can't smoke here. This refers to permission. You technically can smoke here but are forbidden by law.
Kind of like how 'nor' is the opposite of 'or' but you can never say 'not or'.
I wrote невозможно and it allowed it. In all of the sentences I've seen, можно is always paired with an real subject rather than an implied one, so "He may not" rather than "one may not".
Also when I see "cannot", to me "не можно" is more like "one may not know everything" and doesn't have the exact same connotation, whereas невозможноis "it is impossible to know everything", which is the intention of this phrase.
To express impossibility, as opposed to prohibition, shouldn't нельзя be used with the perfective infinitive узнать.?
English sentences require a subject even when making impersonal declarations. So we often use "One cannot..." or "You are not allowed..."
But these are only needed in English, in Russian we omit the subject. So «нельзя ...» and «можно ...» are all that's needed.
(Also, your sentence has spelling errors, not sure if that is important).
Знать requires an object in the accusative case. Всё is neuter and inanimate, so it stays the same in the accusative.
What would be wrong with "Всё нельзя знать."? The only difference between this and the correct solution is word order. How can the correct word order be determined in this sentence?