=WEEKDAY(DATE(C3,D3,1),17) =DAY(DATE(C3,D3+1,0)) =IFERROR(INDEX(輔助表!$A$2:$B$1048538,MATCH(DATE($C$3,$D$3,D6),輔助表!$A$2:$A$1048538,0),2),"") 這三個公式的含義，老師可以給講下嗎？