参考答案

'正确程序
Private Sub C1_Click()
    Dim k As Integer
    k = 0
    While (k < List2.ListCount)
        If List2.Selected(k) = True Then
            List1.AddItem List2.Text
            List2.RemoveItem k
        End If
        k = k + 1
    Wend
End Sub
Private Sub C2_Click()
    List2.AddItem List1.Text
    List1.RemoveItem List1.ListIndex
End Sub