Recently one of my friends told me that there is distinct difference between 'know of something' and 'know about something' expressions. 'know of' is used when you have personal experience with wha... "Know about" vs.

Context Explanation

"know of" - English Language & Usage Stack Exchange Why do you think that He doesn't know him from his schooldays means that he does know him? It would only have that sense if you added something like In fact, he first met him at university. Should I use "did you know" or "do you know" to introduce a fact? I've only seen "did you know" in action.

Insight Material

My logical deduction is that before the "question" (which is not much of a question because you're not asking for an answer), you wouldn't have been sure whether the listener'd known about what you're about to say or not. Should I use "did you know" or "do you know" to introduce a fact? What is the correct usage of phrase "you don't know what you don't know"? Can it be used in formal conversation/writing? In my understanding, ' as we know it ' usually follows a noun phrase and means like The building as we know it = the version/condition of the building we know now.

Final Conclusion

First, I'm not sure about its grammar. Is the 'as' a conjunction? Is it correct to think that 'it' changes to 'them'? E.g., the buildings as we know them Second, a question about its use. Is it possible to use when the preceding ... Grammar and use of 'as we know it' - English Language & Usage Stack ...