It is along or near this fault line that most of California's earthquakes take place, as the two tectonic plates move in different directions.

VOA: special.2011.01.04

I am only counting in one direction, 2 so I have to multiply this whole thing by two because I have to count both directions.

因为我只是在一个方向上计数，所以我要把这些所有乘以,因为我们必须考虑到2个方向。

麻省理工公开课 - 固态化学导论课程节选

Pick any two perpendicular directions Then the same entity, the same arrow which has an existence of its own, independent of axis, can be described by you and me using different numbers.

选取两个互相垂直的方向,这样同样的物体,同一矢量,并且是独立于坐标轴而存在的,可以被你和我用不同的数字来描述

耶鲁公开课 - 基础物理课程节选