1- As yet it is not known whether the crash was the result of an accident. (Original)
2- Yet it is not known whether the crash was the result of an accident.
3- The report remains unfinished as of yet. (Original)
4- The report remains unfinished yet.
In these sentences above, can I use "as (of) yet" instead of "yet" as in 2 and 4 ?
I have one more question: A dictionary says "as yet" implies a meaning "said thing will definitely be changed" Is that always true?
Dictionary: As yet means ‘up to now, but the situation will definitely change’. We only use it in negative contexts.
And gives example :
The film shows you the most typical places, as yet untouched by tourism, and how to get there.