turn one's back on  背对某人，拒绝（帮助），回避

　　Why did you turn your back on him? I told you to take care of him! 你为什么不管他？我跟你说过要好好照顾他的！

　　Now I only turned my back for a second and she was gone. 我只是暂时离开一会，她就不见了。

　　Don't turn your back on him. 不要避开他。

　　If you turn your back on her, she will try to kill you! 如果你不理她的话，会死得很惨！

　　I am not going to listen to you.  我不会再听你的话了。

　　Don't turn your back while I'm talking! 我说话的时候不要假装没听见。