Looking on the internet deeply has found these results:

i did not know this is the most popular phrase on the web. 

Related Comparison

• i never did that or i never do that ?
• I do not believe that or I do not believe in that?
• I didn't know that or I didn't knew that?
• i should not have said that or i should not had said that?
• I did not say so or I did not say that?
• i did not ask that or i did not ask it ?