A3单元格写公式:if(A1==A2,"已到保养时间",if(A1<A2,"已超过保养周期",""))
if(DATESUBDATE(A1,A2,"d")=0,"已到保养时间",if(DATESUBDATE(A1,A2,"d")<0,"已超过保养周期"),"")
在A3单元格设置条件属性,公式---然后写一个if条件