I read a comment in a post (meaning of the phrase "some kind of X") just now and learned an expression "I neither know nor care".
I would like to know whether the expression formal or informal.
I searched the expression on cambridge (https://dictionary.cambridge.org/spellcheck/english-chinese-simplified/?q=I+neither+know+nor+care) and oxford (https://www.oxfordlearnersdictionaries.com/spellcheck/english/?q=I+neither+know+nor+care), none of them has this item.
I am aware that not being included in cambridge does imply necessarily informal, though I don't know somewhere else I can check this.
Is there an easy way to check if an expression formal or informal?
If formal/informal sounds like a matter of opinion, I would prefer the expression in a textbook as formal.