执行下列程序后，鼠标单击窗体，输出结果为

Private Sub Form_Click()

Print "Click"；

End Sub

Private Sub Form_MouseDown(Button As Integer，Shift As Integer，X As Single，Y As Single)

Print "Donw"

End Sub

Private Sub Form_MouseUp(ButtonAs Integer，Shift As Integer，X As Single，Y As Single)

Print "Up"

End Sub

A．DownUpClick

B．ClickDownUp

C．DownClickUp

D．UpDownCliek

血栓闭塞性脉管炎病变主要位于

A．大、中动脉

B．中小静脉

C．中小动静脉，而以动脉为主

D．中小动静脉，而以静脉为主

E．小动脉，而不发生于静脉