a:hover
http://www.w3school.com.cn/cssref/selector_hover.aspa:active
http://www.w3school.com.cn/cssref/pr_pseudo_active.asp
参见:http://www.cnblogs.com/yangfeng/archive/2009/07/25/1530962.html
a:hover
http://www.w3school.com.cn/cssref/selector_hover.aspa:active
http://www.w3school.com.cn/cssref/pr_pseudo_active.asp
参见:http://www.cnblogs.com/yangfeng/archive/2009/07/25/1530962.html