说明：  Flash做动画时会用到Tween类，利用它可以做很多动画效果，例如缓动、弹簧等等。 这里利用flash的Tween类的算法，来做js的Tween算法，并利用它做一些很炫的缓动效果。
(Flash animation will be done using Tween class, it can do a lot of animation effects, such as the relief action, springs and so on. Here the use of Tween-type flash algorithms, as js the Tween algorithm, and use it to do some slow moving很炫effect.)