Now, of course, if your motion is not in a plane, then that plane will change.

当然，如果运动不是始终在一个平面上，平面是会改变的。

youdao

And, to say that the motion actually stays in that plane forever means that this guy will not change direction.

那么说运动将永远保持在平面上，这意味着它的方向不会改变。

youdao

So, if you just look at the position vector, and the velocity vector for any motion at any given time, then together, they determine some plane.

如果你看一下任何时刻运动时的，位置矢量和速度矢量，它们决定了某个平面。

youdao

He saw two Big East assistant coaches on a plane while recruiting, and they cautioned him about installing a motion offense.

WSJ: Big Ten Basketball: Grueling Display of Bumping, Bashing