
General theory of practical method: door hinge and the vertical axis. Lever and the pivoting point. Presenter: Chen Zhonghua Length: 17 min. In: English Year: 2013 Difficulty:1/5 At: Oakland, CA. USA
by Shopmaster on 2013/10/28
General theory of practical method: door hinge and the vertical axis. Lever and the pivoting point. Presenter: Chen Zhonghua Length: 17 min. In: English Year: 2013 Difficulty:1/5 At: Oakland, CA. USA