Unto was used to indicate that something was done or given to someone.
例句
And he said unto him, 'Who is my neighbor?'...他于是对他说道：“谁是我邻居？”I will do unto others what they did to me.我会以其人之道还治其人之身。
PREP
迄至；直至；直到
Unto was used to indicate that something continued until a particular time.
例句
Be ye faithful unto the end.汝等应至死不渝。
英汉词典释义
prep.
对,向
Do unto others as you would have them do unto you.己所不欲,勿施于人。No matter how high one’s position,he must never be a law unto himself.无论一个人的职位有多高,都绝对不能独断专行。