knuckle² v knuckle down phr v [I] informal to start working hard 【非正式】 开始努力工作 knuckle under phr v [I] informal to do what you are told to do, even though you do not want to 【非正式】 屈从,屈服
knuckle down informal to start working hard 【非正式】 开始努力工作 knuckle under informal to do what you are told to do, even though you do not want to 【非正式】 屈从,屈服