有一个名称为Fom1的窗体,上面没有控件,设有以下程序(其中方法PSet(X,Y)的功能是在坐标X,Y处画一个点)。 Dim cmdmave As Boolean Private Sub Form_MouseDown(Button As Integer,Shift As Integer,X As Single,Y As Single) cmdmave=True End Sub Private Sub Form MouseMove(Button As Integer,Shift As Integer,X As Single,Y As Single) If cmdmave Then Form1.PSet(X,Y) End If End Sub Private Sub Form_MouseUp(Button As Integer,Shift As Integer,X As Single,Y As Single) cmdmave=False End Sub 此程序的功能是______。
A) 每按下鼠标键一次,在鼠标所指位置画一个点 B) 按下鼠标键,则在鼠标所指位置画一个点;放开鼠标键,则此点消失 C) 不按鼠标键而拖动鼠标,则沿鼠标拖动的轨迹画一条线 D) 按下鼠标键并拖动鼠标,则沿鼠标拖动的轨迹画一条线,放开鼠标键则结束画线