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

Sometimes we might just directly tell you that's probably the easiest scenario, because when we think about work functions those are usually reported in energy.

有时候我们可能只是直接告诉你,那可能是最简单的情况，因为当我们考虑功函数时,它们经常用能量来记录。

麻省理工公开课 - 化学原理课程节选