每当电视中看到杂技《高空秋千》时，总为演员们的高超技艺所折服．他们升高落低，控制自如，若换成我们，可以想象定会欲高不能，欲低不成．感叹之余，不禁沉思，怎样才能做到荡秋千时可随心所欲呢？······ＯＢＭＮＭＮＡＭＮ我们知道，秋千的运动与单摆很相似，其... Whenever he saw an acrobatic “High Swing” on TV, he was always impressed by the artist’s superb skills. They rise and fall, control freely, and if we change to us, we can imagine that we will not want to be high or low. In addition to sighing, I can’t help but ponder: How can we do whatever we want to do when swinging? ·······················································...