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Hi friends,

Please correct this,

I know john since 5 years

or

I know john last 5 years

(Note: I wanted to say I know john before and not still)
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Aha! The dreaded typo where you accidentally insert or omit the word "not". I know it well. (A notorious example comes to mind: the "Adulterers' Bible", which left the word "not" out of "Thou shalt not commit adultery".)

Anyway, back to your question. You can say:

"I've known John for five years."

"I've known John for the last/past five years."

"I've known John since 2005."
Comments  
Netpicker9I know john last 5 years

[...]

I wanted to say I know john before and not still

I don't really understand what you're trying to say.

You've known John for the last five years but you don't know him now? When did you stop knowing him?

Students: Are you brave enough to let our tutors analyse your pronunciation?
I have corrected here...

I wanted to say I know john before and still....
That was stupid, isin't it?
 Mr Wordy's reply was promoted to an answer.