Also explain the difference between the two, thanks. Why would you have a problem with this? In the first sentence, it seems to me that to know expresses that the speaker experienced the problem/difficulty.
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. Using your example, knowing my rights means that i know i have. Please let me know as soon as you figure it out.
In (2), however, the object of. Recently one of my friends told me that there is distinct difference between 'know of something' and 'know about something' expressions. Can it be used in formal conversation/writing? 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. It's not just you that don't know. Alright, well, for example, like on saturdays, y’know, what i liked to do. 'know of' is used when you have personal.
I know (about) this difficulty/problem.