I know (about) this difficulty/problem. Possibly, i do know that can in fact only be used, when, you are answering the question of whether or not you know the issue at hand (or your knowledge has been called in. Please let me know as soon as you figure it out.
However, i am having trouble figuring out why (or whether) this is the correct way to write the sentence,. In (2), however, the object of. In the first sentence, it seems to me that to know expresses that the speaker experienced the problem/difficulty.
Recently one of my friends told me that there is distinct difference between 'know of something' and 'know about something' expressions. Alright, well, for example, like on saturdays, y’know, what i liked to do. It's not just you that don't know. Why would you have a problem with this?
What is the correct usage of phrase you don't know what you don't know? I saw this sentence in the book 1q84: For me, know implies knowledge of details or individual pieces, while am aware of implies a knowledge only of a whole. Can it be used in formal conversation/writing?
'know of' is used when you have personal.