does it correct to say:i do know anything
if yes,why???
No, it is wrong.

I (do) know something is correct.

I don't know anything is correct.
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but it is not enough for me.dont satisfy me.i want a reason...
because i heared that it is correct if we want to emphasize the act of knowing...
so i want a reason....

thanks again.

Anything is used mainly in questions and negative sentences. But you can say

I know anything can happen.

Say anything you want.

Anything seems to introduce a higher degree of uncertainty in affirmative sentences.
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 BarbaraPA's reply was promoted to an answer.

It's correct! But isn't often used, when you want to make an accent on smth you may use with do, in case if you want to point attention on smth, I do know means that you a definitely know this

Does it correct
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I think you mean Is it correct?