YOU SAID:
You have no idea how much you've forgotten.
INTO JAPANESE
どれだけ忘れているのかわかりません。
BACK INTO ENGLISH
I don't know how much I have forgotten.
INTO JAPANESE
どれだけ忘れたかわかりません。
BACK INTO ENGLISH
I don't know how much I forgot.
INTO JAPANESE
どれだけ忘れたかわかりません。
BACK INTO ENGLISH
I don't know how much I forgot.
That didn't even make that much sense in English.