按照数学家们的分类，三叶形是最简单的纽结。 所谓纽结，它是三维空间中不与自己相交的封闭曲线，或者说是三维空间中与圆周同胚的图形。
The trefoil is the simplest knot in mathematicians' classification.
例如，1519年10月，巴布尔和朋友骑马去Istalif：“草坪是三叶草形的，石榴树镀上了秋天的金黄色，果实全红。”
In October 1519, for instance, Babur rode out to Istalif with friends: “Its lawns were one sheet of trefoil; its pomegranate trees yellowed to autumn splendour, their fruit full red.”
一个新的系统分三组进行了测试，第二组(里塞尔0与封闭三叶形软骨和里塞尔1)能够最佳预测400至425之间的数字骨龄评分。
A new system with three groups was tested, and the second group (Risser 0 with closed triradiate cartilage and Risser 1) was the best predictor of a digital skeletal age score of between 400 and 425.
应用推荐