公式：=IFERROR(LOOKUP(1,0/(COUNTIF($C$1:C1,$A$2:$A$28)=0),$A$2:$A$28),"")
公式2： {=LOOKUP(1,0/FREQUENCY(0,COUNTIF( $C$1:C1 ,$A$2:$A28)),$A$2:$A28)&""}
公式3： {=INDEX($A$2:$A28,MATCH(,COUNTIF( $C$1:C1 ,$A$2:$A28),))&""}
2/3结束：按Ctrl+Shift+Enter
=INDEX(B:B,SMALL(IF(MATCH($B$2:$B$1000&"",$B$2:$B$1000&"",0)=ROW($2:$1000)-1,ROW($2:$1000),4^8),ROW(1:1)))&""
结束：按Ctrl+Shift+Enter
=IF(F2="","",SUMIF(B:B,F2,C:C))
