YOU SAID:
my teacher is the worst
INTO JAPANESE
私の先生は最悪だ
BACK INTO ENGLISH
My teacher sucks.
INTO JAPANESE
私の先生は最悪だ。
BACK INTO ENGLISH
My teacher is the worst.
INTO JAPANESE
私の先生は最悪です。
BACK INTO ENGLISH
My teacher is the worst.
That didn't even make that much sense in English.