YOU SAID:

cant judge a book by its cover

INTO JAPANESE

カバーをして本を裁くことはできない

BACK INTO ENGLISH

I can not judge a book by covering it

INTO JAPANESE

私はそれをカバーして本を判断することはできません

BACK INTO ENGLISH

I can not judge a book covering it

INTO JAPANESE

私はそれをカバーする本を判断することはできません

BACK INTO ENGLISH

I can not judge a book covering it