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我相信你的问题问对了。至少你说清楚了期望的产出是什么。
所以你要做的是：为那些给定值的并集不同的行设置一个值“x”。下面是我的解决方案代码（你可以找到一些注解，这样你就可以理解一切）：

Sub markDistinct()
    ' Declaration of some variables
    Dim rowsNum As Integer
    Dim rgToFilter As Range
    
    ' This code will consider your headers are in the 1st row and your data at 2nd row
    ' Change cell references otherwise
    
    ' Concat formula of the columns of interest (C, E, F)
    ' Place the formula in the first data row of column AN (the one we will fill with "x")
    Range("AN2").Formula = "=CONCATENATE(C2,E2,F2)"
    
    ' Store the number of rows of your data
    rowsNum = Range("C1").End(xlDown).Row
    
    ' Select the range we will filter (column AN)
    Set rgToFilter = Range("AN2:AN" & rowsNum)
    ' Drop down the concat formula to all the rows
    rgToFilter.FillDown
    
    ' Filter by distinct concatenation values
    Range("AN1:AN" & rowsNum).AdvancedFilter Action:=xlFilterInPlace, Unique:=True
    
    ' For each distinct filtered values assign the value "x" in the AN column
    For Each cl In rgToFilter.SpecialCells(xlCellTypeVisible)
        cl.Value = "x"
    Next cl
    
    ' Unfilter data
    ActiveSheet.ShowAllData
    
    ' For each cell in column AN, if its value is different from "x", then empty/clear it 
    For r = 2 To rowsNum
        If Cells(r, "AN") <> "x" Then Cells(r, "AN").ClearContents
    Next r
End Sub

虽然我已经尝试尽可能地使其适应您的需要，但您可能需要进行一些小的更改才能使其适合您的数据。希望这对您有所帮助

标记第一行（多列）

• 标记前几行，即运行以下命令后将保留的行：

ws.Range("A1").CurrentRegion.RemoveDuplicates Columns:=Array(3, 5, 6), Header:=xlYes

Option Explicit

Sub FlagFirstRows()

    Const DST_COL As Long = 40 ' AN
    Const DST_FLAG As String = "x"
    Const SRC_DELIMITER As String = "@"
    Dim sCols(): sCols = VBA.Array(3, 5, 6) ' C, E, F
    
    Dim ws As Worksheet: Set ws = ActiveSheet ' improve!
    
    Dim rg As Range, rCount As Long

    With ws.Range("A1").CurrentRegion
        rCount = .Rows.Count - 1
        If rCount = 0 Then Exit Sub
        Set rg = .Resize(rCount).Offset(1)
    End With
    
    Dim sData(): sData = rg.Value
    Dim dData(): ReDim dData(1 To rCount, 1 To 1)
    
    Dim dict As Object: Set dict = CreateObject("Scripting.Dictionary")
    dict.CompareMode = vbTextCompare
    
    Dim cUB As Long: cUB = UBound(sCols)
    
    Dim r As Long, c As Long, rString As String
    
    For r = 1 To rCount
        rString = sData(r, sCols(0))
        For c = 1 To cUB
            rString = rString & SRC_DELIMITER & sData(r, sCols(c))
        Next c
        If Not dict.Exists(rString) Then
            dict(rString) = Empty
            dData(r, 1) = DST_FLAG
        End If
    Next r
    
    rg.Columns(DST_COL).Value = dData

    MsgBox "First rows flagged.", vbInformation
    
End Sub