YOU SAID:

I Bet you that you never graduated high school

INTO JAPANESE

私はあなたが高校を卒業したことはないことを賭ける

BACK INTO ENGLISH

I bet that you never graduated from high school

INTO JAPANESE

私はあなたが高校を卒業したことはないと確信しています

BACK INTO ENGLISH

I am convinced that you have not graduated from high school

INTO JAPANESE

私はあなたが高校を卒業していないと確信しています

BACK INTO ENGLISH

I am convinced that you have not graduated from high school