后退: draw back; fall back; retrea ...到: 39上: upper; up; upward一步: single-step操作: operate; manipulate; handle取消上一步操作: undo last重复上一步操作: ctrl+r; redo一步操作: single stepping前进到下一步操作: forward上一步: back; previous回到上一级: go to parent转到上一标记: go to previous marker单步操作: one shot operation; one step operation; one-shot operation; one-step operation; single shot operation; single step operation; single-shot operation; single-steoperation; step by step operation非同步操作: operation average calculating失步操作: out-of-step operation同步操作: synchronization operation; synchronous operation位同步操作: bit synchronous operation异步操作: asynchronous operations; operation, auxiliary后退一步: backward one快速后退（后退到最后一页）: rewind重复上一步: repeat last上一步 - 导航先前显示或使用的操作: back - navigates to the previously displayed or used operator初步操作试验: pilot run双重同步操作: dual synchronous operation同步操作系统: symmetric operating system
