Here,he uses a set of buttons attached to a computer to make the silent robot move forward, backward or around in circles.

VOA: special.2009.12.17

So use work out of right-hand side to run left-hand backward.

利用右边输出的功,来驱动左边的热机反方向运行。

麻省理工公开课 - 热力学与动力学课程节选

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

He said the expulsion is obviously a matter of concern to the United States and a step backward,and that North Korea has only brought upon itself further isolation.

VOA: standard.2009.04.15