在窗体上画一个名称为Timer1的计时器、一个名称为Command1的命令按钮和一个名称为Labell的标签。程序如下：
Private Sub Command1_Click()
Timer1．Enabled=True
Timer1．Interval=1000
End Sub
Private Sub Timerl_timer()
Labell．Caption=Time
End Sub
当运行程序后，单击命令按钮，将在标签中显示的内容为

A．Private Sub Form Load()
Show
Text1．Text=" "
Text2．Text=" "
Text2．SetFocus
End Sub
Private Sub Text2_KeyDown(KeyCode As Integer，Shift As Integer)
Text1．Text=Chr(KeyCode-4)
End Sub
B．Private Sub Form_Load()
Show
Text1．Text=" "
Text2．Text=" "
Text2．SetFocus
End Sub
Private Sub Text2_KeyDown(KeyCode As Integer，Shift As Integer)
Text1．Text=Text1．Text+Chr(KeyCode-4)
End Sub
C．Private Sub Form_Load()
Show
Text1．Text=" "
Text2．Text=" "
Text2．SetFocus
End Sub
Private Sub Text2_Click(KeyCode As Integer，Shift As Integer)
Text1．Text=Text1．Text+Chr(KeyCOde-4)
End Sub
D．Private Sub Form_Load()
Show
Text1．Text=" "
Text2．Text=" "
Text2．SetFocus
End Sub
Private Sub Text2_Click(KeyCode As Integer，Shift As Integer)
Text1．Text=Chr(KeyCode-4)
End Sub

A．在队列中只能插入数据
B．在队列中只能删除数据
C．队列是先进先出的线性表
D．队列是先进后出的线性表