leave the track; get derailed; 出轨
single [double] track; 单[双]轨
exceed the bounds; transgress; violate the rule; be against the law; 越轨
put sth. on the right course; put into proper order 纳入正轨
牛津高阶第八版
美国韦氏词典
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维基百科 (自由的百科全书)