Phase velocity and group velocity are included in the teaching materials for university physics classes ,but teachers generally do not go further than just introducing the concepts and deriving the formulas to calculate them .If real applications of these concepts are presented in classroom , better teaching result will be achieved .In this paper ,the theory and im plement of ultraslow light propagation are discussed ,and our goals are two - fold :to provide a valuable case for classroom teaching and to supply interesting scientific information to the general public .%大学物理教学中有相速和群速的介绍，但往往止步于对它们的定义和表达式推导。如果此时适当地拓展它们的应用，会起到事半功倍的作用。本文介绍慢光速研究的理论和实现途径，目的：一为教学提供有价值的案例，二为科普。
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