(idiom) unconsciously; unwittingly

not knowing what to do or being at one's wits' end when facing a sudden or difficult situation

little did one imagine; unaware that (often used to introduce a surprising or contrary fact)

to be incoherent or nonsensical, such that the listener or reader cannot understand the intended point

carried out in such total secrecy that no one notices

to act recklessly; to have no sense of danger (idiom)

to have no sense of shame

having disappeared without a trace; one's whereabouts are unknown

failing to recognize or appreciate someone's good intentions; not knowing what is in one's own best interest

to have no sense of shame; behaving in a brazen or insolent manner

Replying "I don't know" to every question asked, often as a way to avoid responsibility or providing information.

to be completely unaware of or have no idea about something

to be confused and not know what to do or how to react

to live in plenty without appreciating it; not to know when one is well off

failing to recognize social propriety or the status of others; not knowing who is who or how to behave appropriately

one may know a person's face but not their heart; difficult to fully understand someone's true nature

not knowing when to come or leave; lacking a sense of propriety

to eat without tasting the food due to being deeply worried, distressed, or anxious

to have lost consciousness

one can't tell how many; numerous similar cases

To know nothing at all about a matter, specifically lacking knowledge of the beginning, middle, or end.

to know that it is so but not why it is so

in absolute secrecy

the well-fed cannot know how the starving suffer

to know only one side of a matter; to have incomplete information (idiom)

of no importance or having little impact on a situation

known to everyone

showing sustained enthusiasm or energy without becoming tired

not understandable; unclear or garbled in meaning or expression

not knowing the inner workings, the inside story, or the actual state of affairs

not knowing the immensity of heaven and earth; being ignorant of the world's complexity or scale

for some unknown reason; somehow

If you don't want anyone to know, don't do it; if you do something bad, people will inevitably hear about it.

lit. short-lived cicada does not know the seasons; fig. to have a narrow perspective due to limited experience or a short lifespan

forgetting the fate of Ding and Dong; failing to heed historical lessons or the mistakes of predecessors

to go astray and not know how to return to the right path

a person who doesn't manage a household would not be aware how expensive it is

The well-fed cannot know how the starving suffer (idiom).

One who does not know is not guilty; ignorance is a valid excuse for a mistake or a breach of etiquette.

It's a long and intricate story, I hardly know where to start.