The two presidents met for the first time on the sidelines of the G-20 economic conference in London in early April and set in motion what Clinton says is an effort to raise the frequently contentious U.S.-Russian relationship to a higher level.

VOA: standard.2009.05.07

What I did last time was to show you how to handle motion in more than one dimension.

上节课的内容,是用多维矢量描述运动

耶鲁公开课 - 基础物理课程节选

So, time is measured as a parameter along the motion of the particle.

这样,时间就被记为质点运动的一个参数

耶鲁公开课 - 基础物理课程节选