And Sue wore a beautiful white dress with a huge steel-spring bustle in the back.

VOA: special.2009.11.28

Now, we go back to the spring.

现在,回到弹簧的问题上

耶鲁公开课 - 基础物理课程节选

Now, we go back to the spring.

现在,回到弹簧的问题上

耶鲁公开课 - 基础物理课程节选