摘要
从同构的意义上讲，循环群只有整数加群{Z；＋）和模n剩余类加群{Zn；＋），循环群的予群的结构也是非常清楚的，它们还是循环群；最后介绍了判定一个群是循环群的两个充分必要条件。
@@@@Thereare onlyintegeradditive groupand modulo n to residual class additive group in cyclic groupup to isomorphism;the structure of subgroup of cyclic group is very clear, which are stil cyclic group;at last,two sufficient and necessary conditions are introduced for a groupbeinga cyclic group.
