[单项选择题] 假定编写如下事件过程： Private Sub Form_MouseDown(Button As Integer,Shift As Integer,X As Single，Y As

[单项选择题] 假定编写如下事件过程： Private Sub Form_MouseDown(Button As Integer,Shift As Integer,X As Single，Y As Single) 　If(Button and 3)=3 then 　　Print"Hello" 　End if End Sub 程序运行后，为了在窗体上输出“Hello”，应该窗体上执行以下( )操作。

A．只能按下左键并拖动

B．只能按下右键并拖动

C．必须同时按下左、右键并拖动

D．按下左键拖动或按下右键拖动