如果是向后的手势，机器人将减速并停止。

If it moves backwards, the robot will slow down or stop.

youdao

所有的块都可以从任意已知块开始以向前或向后的方向被遍历。

All chunks can be traversed starting from any known chunk in either a forward or backward direction.

youdao

比如，当飞机的螺旋桨疾驰过云层时，会给云一个向后的作用力。

When a plane's propeller, for example, spins through a cloud, the propeller exerts a rearward force.

youdao

If that's all it knows, then in that scenario there is no building or anything else; it continues a trajectory both forward in time and backward in time, and it says that whatever seconds, one second before you set your clock to 0, it would've been on the ground.

如果是这样,在那种模式下,没有楼房或者别的什么,物体的运动轨迹可以沿时间可以向后延伸,也可以向前延伸,不管时间取什么值,在零点前一秒时,物体就在地面上

耶鲁公开课 - 基础物理课程节选