在窗体上画一个名称为Command1的命令按钮，然后编写如下事件过程： Private Sub Command1_Click() Dim a As Integer, s As Integer a = 8 a = 1 Do s = s + a a = a - 1 Loop While a <= 0 Print s; a End Sub 程序运行后，单击命令按钮，则窗体上显示的内容是_____
A
7 9
B
34 0
C
9 7
D
死循环