Now they are falling and in real terms home prices have fallen almost 10% since the peak in 2006.

从2006年房价格最高点算起,现在房价已经,下跌了将近 10%

耶鲁公开课 - 金融市场课程节选

Springs have a natural length; x is measured from that length.

弹簧是有原长的,x 就是从这里起算的

耶鲁公开课 - 基础物理课程节选