YOU SAID:

His mom was doing the wrong thing

INTO JAPANESE

彼のお母さんは間違ったことをしていた

BACK INTO ENGLISH

His mom was doing the wrong

INTO JAPANESE

彼のお母さんは間違っていました

BACK INTO ENGLISH

His mother was wrong

INTO JAPANESE

彼の母親は間違っていた

BACK INTO ENGLISH

His mother was wrong