When we have just a single bond in them molecule, you have all the free rotation you want, you can just spin it around, there's nothing keeping it in place.
当我们在分子力只有一个单键时，你可以随意旋转，你可以让它转起来，没有什么东西能固定住它。
2
Learn to throw the overhand wrist flip upside down with snap and spin from a freestyle Frisbee champion in this free Frisbee video.
学习抛上手手腕翻转倒的卡锁，从自由泳冠军旋转飞盘在这个自由飞盘影片。
3
This paper presents the methods of free flight spin test and rotation balance test in vertical wind tunnel, the design of test model is briefly expounded.