如何实现窗体组合框 允许多值添加数据

Private Sub 乡名_AfterUpdate()
Dim I As Integer, strList As String
    With 乡名
        For I = 1 To .ListCount
            strList = IIf(Nz(strList) = "", "", strList & ";") & .ItemData(I)
        Next
        If Nz(.Text) <> "" Then
            If InStr(1, .Tag, .Text) = 0 And InStr(1, strList, .Text) > 0 Then
                .Value = IIf(Nz(.Tag) = "", "", .Tag & "、") & .Text
            End If
            .Tag = .Text
        Else
            .Tag = ""
        End If
    End With
End Sub