關鍵字為空 否則往上取非關鍵字 (13890)

D3=IF(COUNTIF(F:F,C3),"",LOOKUP(1,0/(COUNTIF(F:F,C$2:C2)=0),C$2:C2))

另解=REPT(LOOKUP(1,0/(COUNTIF(F:F,C$2:C2)=0),C$2:C2),COUNTIF(F:F,C3)=0)