问题详情

编写如下代码：
Dim Flag As Boolean
Private Sub Form. MouseDown (Button As Integer,
Shift As Integer, X As Single, Y As Single)
Flag = True
End Sub
Private Sub Form. MouseMove (Button As Integer,
Shift As Integer, X As Single, Y As Single)
Flag = False
End Sub
Private Sub Form_ MouseUp (Button As Integer,
Shift As Integer, X As Single, Y As Single)
If Flag = False Then
Print "DDDD"
End If
End Sub
程序运行后，如果想在窗体上输出DDDD，则应执行的操作为______。请帮忙给出正确答案和分析，谢谢！