excel表格里有个公式看不懂“=IF((A228-YEAR(O226)>=20),15,(IF((A228-YEAR(O226))=10,ROUNDDOWN((O226-DATE(YEAR(O226),1,1))/365*5.25+(DATE(YEAR(O226),12,31)-O226)/365*10.25,0),IF((A228-YEAR(O226))>20,15,IF((A228-YEAR(O226))>10,10,IF((A228-YEAR(O226))>1,5,IF(A228-YEAR(O226)>0,(DATE(YEAR(O226),12,31)-O226)/365*5.25,0)))))))”请高手赐教呀!