turn one's back 不愿帮助，抛弃，拒绝，不理睬

　　Jack turned his back on me when I asked him for help.

　　当我请求Jack帮助时，他完全不理会。

　　I can't turn my back on my uncle Steve, he's old and sick now.

　　我叔叔Steve又老又病，我不能丢下他不管。

　　疯狂练习吧！