A.aaB.AAC.AaD.aA
A.当前时间B.实例化对象的时间C.00:00:00D.08:00:02
A.var r1=Math.round(aNum*100)/100;B.var r1=Math.round(aNum)*100/100;C.var r1=Math.round(aNum);D.var r1=Math.round(aNum*1000)/100;