goody two-shoes-------自以为是的人

英文释义
A smug, self-righteous person who is offensively proud of his or her virtue.

例句
As a child my sister was a goody two-shoes who enjoyed telling our parents about my minor misdeeds.
我姐姐小时候自以为是，喜欢把我犯的一些小错误告诉我的父母。