:nth-child

:nth-child(2n)/nth-child(even)偶数 

:nth-child(2n+1)/nth-child(odd)奇数

:nth-child(-n+x) 选中前x个

:nth-child(n+x) 第X个开始之后的全部

原文地址:https://www.cnblogs.com/sphjy/p/11309735.html