[5分]请教一个关于列表框的问题

Private Sub Command4_Click()
    Dim i As Integer
    Dim str  As String
    Dim is存在 As Boolean
    is存在 = False
    str = List1.Column(0)
    For i = 0 To List2.ListCount - 1    '查找在List2中有没有与List1选中的相同的内容
        If List2.Column(0, i) = str Then
            is存在 = True
            Exit For
        End If
    Next i
    If is存在 = False Then '在List2中没有与List1选中的相同的内容,则添加到List2中
        Me.List2.AddItem List1.Column(0)
        Me.List2.Requery
    End If
End Sub

Private Sub Command5_Click()
    Me.List2.RowSource = ""
End Sub

Private Sub Command6_Click()
    If Me.List2.ListCount > 0 Then
        List2.RemoveItem List2.Column(0)
    End If
End Sub

Private Sub Form_Load()
    Me.List1.RowSourceType = "值列表"
    Me.List1.RowSource = ""
    Dim rst As DAO.Recordset
    Set rst = CurrentDb.OpenRecordset("qryclgl", dbOpenDynaset)
    For i = 0 To rst.Fields.Count - 1
        Me.List1.AddItem Item:=rst.Fields(i).Name
    Next
    Me.List1.SetFocus
    List1.Selected(0) = True  '这是窗体一打开让list1列表框的ID是被选定状态
    rst.Close
    Set rst = Nothing
End Sub