corry Wrote:I think you left out the, limit output to only, bit.

Not really, but perhaps I didn't phrase it clearly enough.

"You said that having heard and understood something, then you won't make any mistakes (about that something)."

It's still not a tautology. You can hear and understand something, and then output that very thing, but make a mistake in your attempt. People do it all the time.

You didn't say "It seems like if you limit output to only the things that you have heard and understood in your input so well that you won't make a mistake in your output then you wont make any mistakes and there wont be anything to fossilize." That's a tautology. It's also unachievable.

undead_saif Wrote:because it's not an education environment, I don't get the chance to think about and correct my mistakes.to solve this.

Your English will improve when you throw that out. You don't think you do.