1. 英語通常說 turn one’s back on sb，很少說 turn one's back to sb。
2. turn one’s back on sb 的本義是：把背朝向某人
    turn one’s back on sb 引申義是：避開或拒絕接受某人
3. 例句：
   He turned his back on his family when he became famous. 他成名以后對自己家里的人連理都不理。