YOU SAID:
My sister has the whitest teeth I ever came across
INTO JAPANESE
私の妹は私が今までに出会った最も白い歯
BACK INTO ENGLISH
My sister is the whitest teeth I ever came across.
INTO JAPANESE
私の妹は、私が今までに出会った最も白い歯です。
BACK INTO ENGLISH
My sister is the whitest teeth I ever came across.
Come on, you can do better than that.